This is a pretty darn simple snippet that I learned from a site (don't remember the name). This is just the working Javascript which i managed to "easily" replicate :P
Hopefully this will be useful for you guys.
Note, this won't graph anything unless you have the html/css (i didn't provide that).
//Class for operators
function Operator(input) {
this.operator = input;
if (!input) {
console.log("Operator has no input.");
}
this.solve = function(segment1, segment2, x) {
var v1 = segment1.coefficient;
if (segment1.type=="variable") {
v1 = x;
}
var v2 = segment2.coefficient;
if (segment2.type=="variable") {
v2 = x;
}
if (this.operator=="+") {
return new Segment(v1 + v2);
} else if (this.operator=="-") {
return new Segment(v1 - v2);
} else if (this.operator=="*") {
return new Segment(v1 * v2);
} else if (this.operator=="/") {
return new Segment(v1 / v2);
} else if (this.operator=="^") {
return new Segment(Math.pow(v1, v2));
}
};
}
//Class for special functions
function MathFunction(input) {
this.f=input;
if (!input) {
console.log("Math function has no input.");
}
this.solve = function(segment) {
var v = segment.coefficient;
if (this.f=="sin") {
return new Segment(Math.sin(v));
} else if (this.f=="cos") {
return new Segment(Math.cos(v));
} else if (this.f=="tan") {
return new Segment(Math.tan(v));
} else if (this.f=="asin") {
return new Segment(Math.asin(v));
} else if (this.f=="acos") {
return new Segment(Math.acos(v));
} else if (this.f=="atan") {
return new Segment(Math.atan(v));
} else if (this.f=="abs") {
return new Segment(Math.abs(v));
}
};
}
//Class for a segment of math (a container)
function Segment(input) {
this.sections = [];
this.type="section";
this.operator=0;
this.coefficient=0;
this.mathFunction=0;
this.variable="";
var removeBrackets = function(value) {
if (!value) return "";
//While there are brackets around the string
while (value.substr(0, 1)=="(" && value.substr(value.length-1, 1)==")") {
var openBrackets=1;
//See if the end bracket closes the opening bracket or not
for (var i=1; i<value.length&&openBrackets>0; i++) {
if (value.substr(i, 1)=="(") openBrackets++;
if (value.substr(i, 1)==")") openBrackets--;
}
i-=1;
//If it corresponds to different brackets, do nothing
if (openBrackets!==0 || i!=value.length-1) {
break;
//Otherwise, remove the brackets, continue loop to see if there are more
} else {
value=value.substring(1, value.length-1);
}
}
return value;
};
var findLast = function(operator, value) {
//Keep searching for the next last sign if the one found is within brackets
var inBrackets=true;
var index=-1;
if (operator!="^") {
index=value.lastIndexOf(operator);
} else {
index=value.indexOf(operator); //Look for the first instead of last if it's an exponent
}
var operators="+-/*^";
while (inBrackets) {
var openBrackets=0;
//Find how many brackets are opened or closed at a given point in the string
for (var i=0; i<value.length; i++) {
if (value.substr(i, 1)=="(") {
openBrackets++;
} else if (value.substr(i, 1)==")") {
openBrackets--;
}
if (i==index) {
//If no brackets are open (and if the operator is actually - and not just a minus sign), break the loop.
if ((openBrackets===0 && (operator!="-" || (i>0 && operators.indexOf(value.substr(i-1, 1))==-1) || i===0)) || (openBrackets==1 && operator=="(")) {
inBrackets=false;
break;
//Otherwise, find the next operator, and loop through again to see if that one is in brackets
} else {
if (operator!="^") {
index = value.substring(0, index).lastIndexOf(operator);
} else {
var nextOperator = value.substring(index+1).indexOf(operator);
if (nextOperator==-1) {
index=-1;
} else {
index = (index+1+value.substring(index+1).indexOf(operator));
}
}
}
}
}
//If no more operators are found, break the loop
if (index==-1) {
inBrackets=false;
}
}
return index;
};
var findLastTrig = function(trig, value) {
var matches=0;
var index=-1;
var r=0;
if (trig=="sin") {
r=/(a)?sin/g;
} else if (trig=="cos") {
r=/(a)?cos/g;
} else if (trig=="tan") {
r=/(a)?tan/g;
} else {
return -1;
}
for (matches=r.exec(value); matches; matches=r.exec(value)) if (RegExp.$1 != "a") index=matches.index;
var inBrackets=true;
while (inBrackets && index!=-1) {
var openBrackets=0;
//Find how many brackets are opened or closed at a given point in the string
for (var i=0; i<value.length; i++) {
if (value.substr(i, 1)=="(") {
openBrackets++;
} else if (value.substr(i, 1)==")") {
openBrackets--;
}
if (i==index) {
//If no brackets are open (and if the operator is actually - and not just a minus sign), break the loop.
if (openBrackets===0) {
inBrackets=false;
break;
//Otherwise, find the next operator, and loop through again to see if that one is in brackets
} else {
var sub = value.substring(0, index);
index=-1;
for (matches=r.exec(sub); matches; matches=r.exec(sub)) if (RegExp.$1 != "a") index=matches.index;
}
}
}
//If no more operators are found, break the loop
if (index==-1) {
inBrackets=false;
}
}
return index;
};
//Specifically for finding brackets that can be used for multiplication
var findMultiplicationBrackets = function(value) {
//Keep searching for the next last sign if the one found is within brackets
var inBracketsOpen=true;
var inBracketsClosed=true;
var indexOpen=-1;
var indexClosed=-1;
var operators="+-/*^sincostanabs";
indexOpen=value.lastIndexOf("(");
indexClosed=value.lastIndexOf(")");
while (inBracketsOpen || inBracketsClosed) {
var openBrackets=0;
//Find how many brackets are opened or closed at a given point in the string
for (var i=0; i<value.length; i++) {
if (value.substr(i, 1)=="(") {
openBrackets++;
} else if (value.substr(i, 1)==")") {
openBrackets--;
}
if (i==indexOpen && inBracketsOpen) {
if (openBrackets==1 && i!==0 && operators.indexOf(value.substr(i-1, 1))==-1) {
inBracketsOpen=false;
//Otherwise, find the next operator, and loop through again to see if that one is in brackets
} else {
indexOpen = value.substring(0, indexOpen).lastIndexOf("(");
}
}
if (i==indexClosed && inBracketsClosed) {
if (openBrackets===0 && i<value.length-1 && operators.indexOf(value.substr(i+1, 1))==-1) {
inBracketsClosed=false;
//Otherwise, find the next operator, and loop through again to see if that one is in brackets
} else {
indexClosed = value.substring(0, indexClosed).lastIndexOf(")");
}
}
}
//If no more operators are found, break the loop
if (indexOpen==-1) {
inBracketsOpen=false;
}
if (indexClosed==-1) {
inBracketsClosed=false;
}
}
if (indexClosed>indexOpen && indexClosed!=-1) {
return indexClosed;
} else {
return indexOpen;
}
};
//Recursively solve children
this.solve = function(x) {
if (!x) x=0;
if (this.type=="value") {
return this;
} else if (this.type=="variable") {
return new Segment(x);
} else if (this.type=="function") {
return this.mathFunction.solve(this.sections[0].solve(x));
} else {
if (this.sections.length==1) {
return this.sections[0].solve(x);
} else if (this.sections.length==2) {
return this.operator.solve(this.sections[0].solve(x), this.sections[1].solve(x), x);
}
}
};
//Outputs the final answer
this.result = function(x) {
return this.solve(x).coefficient;
};
this.display = function(x) {
if (this.type=="value") return this.coefficient;
if (this.type=="variable") return "x";
if (this.type=="function") return this.mathFunction.f;
var str = "<div class='group'>";
for (var i=0; i<this.sections.length; i++) {
str+=this.sections[i].display(x);
if (i===0 && this.operator) {
str+="<div class='group operator'>" + this.operator.operator + "</div>";
}
}
str+="<div class='answer'>= " + this.solve().coefficient + "</div>";
str+="</div>";
return str;
};
//constructor
if (input!==undefined) {
if (typeof(input)=="string") {
//Remove excess whitespace
input = input.replace(/\s/g, "");
//get rid of unnecessary brackets surrounding the section
input = removeBrackets(input);
//Find the last instance of each operator in the string
var addition = findLast("+", input);
var subtraction = findLast("-", input);
var division = findLast("/", input);
var exponent = findLast("^", input); //Find the first exponent, since those work in reverse
var bracket1 = findLast("(", input);
var sin = findLastTrig("sin", input);
var cos = findLastTrig("cos", input);
var tan = findLastTrig("tan", input);
var asin = findLast("asin", input);
var acos = findLast("acos", input);
var atan = findLast("atan", input);
var abs = findLast("abs", input);
var multiplication = findLast("*", input);
var multiplication2 = findMultiplicationBrackets(input); //Find brackets that are the same as multiplication
var functionMultiplication = -1;
if (sin>multiplication) functionMultiplication=sin;
if (cos>multiplication) functionMultiplication=cos;
if (tan>multiplication) functionMultiplication=tan;
if (asin>multiplication) functionMultiplication=asin;
if (acos>multiplication) functionMultiplication=acos;
if (atan>multiplication) functionMultiplication=atan;
if (abs>multiplication) functionMultiplication=abs;
//Push back each half of the equation into a section, in reverse order of operations
if (addition != -1 && (subtraction == -1 || addition>subtraction)) {
this.sections.push(new Segment(input.substring(0, addition)));
this.sections.push(new Segment(input.substring(addition+1)));
this.operator = new Operator("+");
} else if (subtraction != -1) {
if (subtraction>0) {
this.sections.push(new Segment(input.substring(0, subtraction)));
} else {
this.sections.push(new Segment(0));
}
this.sections.push(new Segment(input.substring(subtraction+1)));
this.operator = new Operator("-");
} else if (functionMultiplication >0 && functionMultiplication > multiplication && functionMultiplication > division) {
this.sections.push(new Segment(input.substring(0, functionMultiplication)));
this.sections.push(new Segment(input.substring(functionMultiplication)));
this.operator = new Operator("*");
} else if (multiplication2 != -1 && (division == -1 || multiplication>division) && (multiplication == -1 || multiplication2>multiplication)) {
this.sections.push(new Segment(input.substring(0, multiplication2)));
this.sections.push(new Segment(input.substring(multiplication2)));
this.operator = new Operator("*");
} else if (multiplication != -1 && (division == -1 || multiplication>division)) {
this.sections.push(new Segment(input.substring(0, multiplication)));
this.sections.push(new Segment(input.substring(multiplication+1)));
this.operator = new Operator("*");
} else if (division != -1) {
this.sections.push(new Segment(input.substring(0, division)));
this.sections.push(new Segment(input.substring(division+1)));
this.operator = new Operator("/");
} else if (exponent != -1) {
this.sections.push(new Segment(input.substring(0, exponent)));
this.sections.push(new Segment(input.substring(exponent+1)));
this.operator = new Operator("^");
} else if (sin != -1 && (cos == -1 || sin>cos) && (tan == -1 || sin>tan) && (asin == -1 || sin>asin) && (acos == -1 || sin>acos) && (atan == -1 || sin>atan) && (abs == -1 || sin>abs)) {
this.sections.push(new Segment(input.substring(sin+3)));
this.mathFunction = new MathFunction("sin");
this.type = "function";
} else if (cos != -1 && (tan == -1 || cos>tan) && (asin == -1 || cos>asin) && (acos == -1 || cos>acos) && (atan == -1 || cos>atan) && (abs == -1 || cos>abs)) {
this.sections.push(new Segment(input.substring(cos+3)));
this.mathFunction = new MathFunction("cos");
this.type = "function";
} else if (tan != -1 && (asin == -1 || tan>asin) && (acos == -1 || tan>acos) && (atan == -1 || tan>atan) && (abs == -1 || tan>abs)) {
this.sections.push(new Segment(input.substring(tan+3)));
this.mathFunction = new MathFunction("tan");
this.type = "function";
} else if (asin != -1 && (acos == -1 || asin>acos) && (atan == -1 || asin>atan) && (abs == -1 || asin>abs)) {
this.sections.push(new Segment(input.substring(asin+4)));
this.mathFunction = new MathFunction("asin");
this.type = "function";
} else if (acos != -1 && (atan == -1 || acos>atan) && (abs == -1 || acos>abs)) {
this.sections.push(new Segment(input.substring(acos+4)));
this.mathFunction = new MathFunction("acos");
this.type = "function";
} else if (atan != -1 && (abs == -1 || atan>abs)) {
this.sections.push(new Segment(input.substring(atan+4)));
this.mathFunction = new MathFunction("atan");
this.type = "function";
} else if (abs != -1) {
this.sections.push(new Segment(input.substring(abs+3)));
this.mathFunction = new MathFunction("abs");
this.type = "function";
} else if (bracket1 != -1) {
var openBrackets=1;
for (var i=bracket1+1; i<input.length&&openBrackets>0; i++) {
if (input.substr(i, 1)=="(") openBrackets++;
if (input.substr(i, 1)==")") openBrackets--;
}
if (openBrackets===0) {
var bracket2=i-1;
if (bracket1>0) this.sections.push(new Segment(input.substring(0, bracket1)));
if (bracket2-bracket1!=1) this.sections.push(new Segment(input.substring(bracket1+1, bracket2)));
if (bracket2!=input.length-1) this.sections.push(new Segment(input.substring(bracket2+1)));
this.operator = new Operator("*");
} else {
console.log("Brackets nesting error: " + input);
}
//If there are no operators, just push the input itself
} else {
var xLocation=input.toLowerCase().indexOf("x");
if (xLocation!=-1) {
if (xLocation>0) {
this.sections.push(new Segment(input.substring(0, xLocation)));
this.sections.push(new Segment("x"));
this.operator=new Operator("*");
} else {
this.variable="x";
this.type="variable";
}
} else {
this.coefficient = parseFloat(input);
this.type = "value";
}
}
} else if (typeof(input)=="number") {
this.coefficient = input;
this.type = "value";
}
} else {
console.log("Segment has no input.");
}
}
//One point on a graph
function Point(x, y) {
this.x = x || 0;
this.y = y || 0;
}
//MathFunction to create graphs
function Graph(value, width, height, rangeX, rangeY) {
var autoRange=false;
//Default params
if (rangeX===undefined) {
rangeX=10;
}
if (rangeY===undefined) {
autoRange = true;
}
//Properties
this.expression = new Segment(value);
this.points = [];
this.canvas = document.createElement("canvas");
this.canvas.width=width || 400;
this.canvas.height=height || 400;
this.min=undefined;
this.max=undefined;
this.x1 = 0-Math.abs(rangeX);
this.x2 = 0+Math.abs(rangeX);
this.y1 = 0-Math.abs(rangeY);
this.y2 = 0+Math.abs(rangeY);
var startMouse = new Point(0, 0);
var mousePos = new Point(0, 0);
var timer=0;
var stage=0;
var img=0;
var magnitudeX = 0;
var magnitudeY = 0;
//Gets minimum y value in the set of points
this.getMin = function() {
if (this.min===undefined) {
if (this.points.length>0) {
var min = this.points[0].y;
for (var i=1; i<this.points.length; i++) {
if (this.points[i].y<min) min = this.points[i].y;
}
this.min=min;
return min;
} else {
return 0;
}
} else {
return this.min;
}
};
//Gets maximum y value in the set of points
this.getMax = function() {
if (this.max===undefined) {
if (this.points.length>0) {
var max = this.points[0].y;
for (var i=1; i<this.points.length; i++) {
if (this.points[i].y>max) max = this.points[i].y;
}
this.max=max;
return max;
} else {
return 0;
}
} else {
return this.max;
}
};
//Updates the points and graph
this.update = function() {
var accuracy = (this.x2-this.x1)/this.canvas.width;
this.points = [];
for (var i=this.x1; i<=this.x2; i+=accuracy) {
this.points.push(new Point(i, this.expression.result(i)));
}
if (autoRange) {
if (this.getMax()-this.getMin()>100000) {
this.y1=-100;
this.y2=100;
} else {
this.y1=this.getMin()-5;
this.y2=this.getMax()+5;
}
autoRange = false;
}
magnitudeX = Math.ceil(Math.log(this.x2-this.x1));
magnitudeY = Math.ceil(Math.log(this.y2-this.y1));
this.redraw();
};
var drawAxes = function(_x1, _x2, _y1, _y2, redraw) {
stage.strokeStyle="#bdc3c7";
stage.fillStyle="#bdc3c7";
var limit=0;
var i=0;
//Draw the y axis if it is in the view
if (0>=_x1-30 && 0<=_x2+30) {
stage.lineWidth=2;
stage.beginPath();
stage.moveTo(this.canvas.width/2-(((_x2+_x1)/2)/(_x2-_x1))*this.canvas.width, 0);
stage.lineTo(this.canvas.width/2-(((_x2+_x1)/2)/(_x2-_x1))*this.canvas.width, this.canvas.height);
stage.closePath();
stage.stroke();
stage.textAlign = "right";
stage.textBaseline="middle";
stage.lineWidth=1;
limit = (Math.abs(_y2)>Math.abs(_y1))?Math.abs(_y2):Math.abs(_y1);
for (i=0; i<=limit; i+=Math.pow(10, Math.floor(Math.log(_y2-_y1) / Math.LN10))/4) {
if (i===0) continue;
if (i<=_y2+50) {
if (redraw || (i>=this.y2-50)) {
stage.beginPath();
stage.moveTo(this.canvas.width/2-(((_x2+_x1)/2)/(_x2-_x1))*this.canvas.width-5, this.canvas.height-((i-_y1)/(_y2-_y1))*this.canvas.height);
stage.lineTo(this.canvas.width/2-(((_x2+_x1)/2)/(_x2-_x1))*this.canvas.width+5, this.canvas.height-((i-_y1)/(_y2-_y1))*this.canvas.height);
stage.closePath();
stage.stroke();
stage.fillText(""+(Math.round(i*100)/100), this.canvas.width/2-(((_x2+_x1)/2)/(_x2-_x1))*this.canvas.width-8, this.canvas.height-((i-_y1)/(_y2-_y1))*this.canvas.height);
}
}
if (i>=_y1-50) {
if (redraw || (-i<=this.y1+50)) {
stage.beginPath();
stage.moveTo(this.canvas.width/2-(((_x2+_x1)/2)/(_x2-_x1))*this.canvas.width-5, this.canvas.height-((-i-_y1)/(_y2-_y1))*this.canvas.height);
stage.lineTo(this.canvas.width/2-(((_x2+_x1)/2)/(_x2-_x1))*this.canvas.width+5, this.canvas.height-((-i-_y1)/(_y2-_y1))*this.canvas.height);
stage.closePath();
stage.stroke();
stage.fillText(""+(Math.round(-i*100)/100), this.canvas.width/2-(((_x2+_x1)/2)/(_x2-_x1))*this.canvas.width-8, this.canvas.height-((-i-_y1)/(_y2-_y1))*this.canvas.height);
}
}
}
}
//Draw the x axis if it is in the view
if (0>=_y1-50 && 0<=_y2+50) {
stage.lineWidth=2;
stage.beginPath();
stage.moveTo(0, this.canvas.height/2+(((_y2+_y1)/2)/(_y2-_y1))*this.canvas.height);
stage.lineTo(this.canvas.width, this.canvas.height/2+(((_y2+_y1)/2)/(_y2-_y1))*this.canvas.height);
stage.closePath();
stage.stroke();
stage.textAlign = "center";
stage.textBaseline="top";
stage.lineWidth=1;
limit = (Math.abs(_x2)>Math.abs(_x1))?Math.abs(_x2):Math.abs(_x1);
for (i=0; i<=limit; i+=Math.pow(10, Math.floor(Math.log(_x2-_x1) / Math.LN10))/4) {
if (i===0) continue;
if (i<=_x2+50) {
if (redraw || (i>=this.x2-50)) {
stage.beginPath();
stage.moveTo(((i-_x1)/(_x2-_x1))*this.canvas.width, this.canvas.height/2+(((_y2+_y1)/2)/(_y2-_y1))*this.canvas.height-5);
stage.lineTo(((i-_x1)/(_x2-_x1))*this.canvas.width, this.canvas.height/2+(((_y2+_y1)/2)/(_y2-_y1))*this.canvas.height+5);
stage.closePath();
stage.stroke();
stage.fillText(""+(Math.round(i*100)/100), ((i-_x1)/(_x2-_x1))*this.canvas.width, this.canvas.height/2+(((_y2+_y1)/2)/(_y2-_y1))*this.canvas.height+8);
}
}
if (i>=_x1-50) {
if (redraw || (-i<=this.x1+50)) {
stage.beginPath();
stage.moveTo(((-i-_x1)/(_x2-_x1))*this.canvas.width, this.canvas.height/2+(((_y2+_y1)/2)/(_y2-_y1))*this.canvas.height-5);
stage.lineTo(((-i-_x1)/(_x2-_x1))*this.canvas.width, this.canvas.height/2+(((_y2+_y1)/2)/(_y2-_y1))*this.canvas.height+5);
stage.closePath();
stage.stroke();
stage.fillText(""+(Math.round(-i*100)/100), ((-i-_x1)/(_x2-_x1))*this.canvas.width, this.canvas.height/2+(((_y2+_y1)/2)/(_y2-_y1))*this.canvas.height+8);
}
}
}
}
}.bind(this);
//Updates the canvas
this.redraw = function() {
if (this.points.length>1) {
stage.clearRect(0, 0, this.canvas.width, this.canvas.height);
stage.lineCap="round";
var offsetY = -this.y1;
drawAxes(this.x1, this.x2, this.y1, this.y2, true);
//Draw all the points
stage.strokeStyle="#171717";
stage.lineWidth=1;
stage.beginPath();
stage.moveTo(0, this.canvas.height-((this.points[0].y+offsetY)/(this.y2-this.y1))*this.canvas.height);
for (var i=1; i<this.points.length; i++) {
if (Math.abs((this.canvas.height-((this.points[i].y+offsetY)/(this.y2-this.y1))*this.canvas.height)-(this.canvas.height-((this.points[i-1].y+offsetY)/(this.y2-this.y1))*this.canvas.height))<=this.canvas.height) {
stage.lineTo((i/this.points.length)*this.canvas.width, this.canvas.height-((this.points[i].y+offsetY)/(this.y2-this.y1))*this.canvas.height);
}
stage.moveTo((i/this.points.length)*this.canvas.width, this.canvas.height-((this.points[i].y+offsetY)/(this.y2-this.y1))*this.canvas.height);
}
stage.closePath();
stage.stroke();
img = stage.getImageData(0, 0, this.canvas.width, this.canvas.height);
} else {
console.log("Not enough points to graph.");
}
};
this.setRange = function(_x1, _x2, _y1, _y2) {
this.x1=_x1;
this.x2=_x2;
this.y1=_y1;
this.y2=_y2;
this.update();
};
var getMousePos = function(evt) {
var rect = this.canvas.getBoundingClientRect();
var root = document.documentElement;
// return relative mouse position
var mouseX = evt.clientX - rect.left - root.scrollLeft;
var mouseY = evt.clientY - rect.top - root.scrollTop;
return new Point(mouseX, mouseY);
}.bind(this);
var startDrag = function(event) {
document.addEventListener("mousemove", dragMouse, false);
document.addEventListener("mouseup", endDrag, false);
this.canvas.removeEventListener("mouseover", startMouseOver, false);
this.canvas.removeEventListener("mousemove", moveMouse, false);
startMouse = getMousePos(event);
}.bind(this);
var redrawLine = function() {
var offsetX = ((mousePos.x-startMouse.x)/this.canvas.width)*(this.x2-this.x1);
var offsetY = ((mousePos.y-startMouse.y)/this.canvas.height)*(this.y2-this.y1);
this.setRange(this.x1-offsetX, this.x2-offsetX, this.y1+offsetY, this.y2+offsetY);
startMouse = mousePos;
}.bind(this);
var dragMouse = function(event) {
stage.clearRect(0, 0, this.canvas.width, this.canvas.height);
mousePos = getMousePos(event);
var newx1 = this.x1-((mousePos.x-startMouse.x)/this.canvas.width)*(this.x2-this.x1);
var newx2 = this.x2-((mousePos.x-startMouse.x)/this.canvas.width)*(this.x2-this.x1);
var newy1 = this.y1+((mousePos.y-startMouse.y)/this.canvas.height)*(this.y2-this.y1);
var newy2 = this.y2+((mousePos.y-startMouse.y)/this.canvas.height)*(this.y2-this.y1);
if (Math.abs(newx1-this.x1)>this.canvas.width/2 || Math.abs(newy1-this.y1)>this.canvas.height/2) {
redrawLine();
} else {
drawAxes(newx1, newx2, newy1, newy2, false);
stage.putImageData(img, mousePos.x-startMouse.x, mousePos.y-startMouse.y);
}
}.bind(this);
var endDrag = function(event) {
document.removeEventListener("mousemove", dragMouse, false);
document.removeEventListener("mouseup", endDrag, false);
this.canvas.addEventListener("mouseover", startMouseOver, false);
this.canvas.addEventListener("mousemove", moveMouse, false);
mousePos = getMousePos(event);
var offsetX = ((mousePos.x-startMouse.x)/this.canvas.width)*(this.x2-this.x1);
var offsetY = ((mousePos.y-startMouse.y)/this.canvas.height)*(this.y2-this.y1);
this.setRange(this.x1-offsetX, this.x2-offsetX, this.y1+offsetY, this.y2+offsetY);
}.bind(this);
var startMouseOver = function(event) {
this.canvas.addEventListener("mousemove", moveMouse, false);
this.canvas.addEventListener("mouseout", endMouseOver, false);
}.bind(this);
var moveMouse = function(event) {
stage.clearRect(0, 0, this.canvas.width, this.canvas.height);
stage.putImageData(img, 0, 0);
mousePos = getMousePos(event);
var offsetY = -this.y1;
//Draw the coordinate
stage.fillStyle="#171717";
stage.beginPath();
stage.arc(mousePos.x, this.canvas.height-((this.points[Math.round(mousePos.x/this.canvas.width*this.points.length)].y+offsetY)/(this.y2-this.y1))*this.canvas.height, 4, 0, 2*Math.PI);
stage.closePath();
stage.fill();
stage.fillStyle="#000";
stage.strokeStyle="#FFF";
stage.lineWidth=4;
stage.textBaseline="alphabetic";
var txt="(" + (Math.round(this.points[Math.round(mousePos.x/this.canvas.width*this.points.length)].x*100)/100).toFixed(2) + ", " + (Math.round(this.points[Math.round(mousePos.x/this.canvas.width*this.points.length)].y*100)/100).toFixed(2) + ")";
if (mousePos.x<stage.measureText(txt).width/2+2) {
stage.textAlign = "left";
} else if (mousePos.x>this.canvas.width-stage.measureText(txt).width/2-2) {
stage.textAlign = "right";
} else {
stage.textAlign = "center";
}
stage.strokeText(txt, mousePos.x, -10+this.canvas.height-((this.points[Math.round(mousePos.x/this.canvas.width*this.points.length)].y+offsetY)/(this.y2-this.y1))*this.canvas.height);
stage.fillText(txt, mousePos.x, -10+this.canvas.height-((this.points[Math.round(mousePos.x/this.canvas.width*this.points.length)].y+offsetY)/(this.y2-this.y1))*this.canvas.height);
}.bind(this);
var endMouseOver = function(event) {
this.canvas.removeEventListener("mousemove", moveMouse, false);
this.canvas.removeEventListener("mouseout", endMouseOver, false);
stage.clearRect(0, 0, this.canvas.width, this.canvas.height);
stage.putImageData(img, 0, 0);
}.bind(this);
//Returns the canvas element
this.getCanvas = function() {
return this.canvas;
};
//If canvas drawing is supported
if (this.canvas.getContext) {
//Get the canvas context to draw onto
stage = this.canvas.getContext("2d");
stage.font = "12px sans-serif";
this.canvas.style.backgroundColor="#FFF";
//Make points
this.update();
this.canvas.addEventListener("mousedown", startDrag, false);
this.canvas.addEventListener("mouseover", startMouseOver, false);
} else {
console.log("Canvas not supported in this browser.");
this.canvas = document.createElement("div");
this.canvas.innerHTML="Canvas is not supported in this browser.";
}
}
//Module for input checking and parsing
var XCalc = (function() {
var worker={};
//Checks to see if brackets are properly nested in a string
worker.properBrackets = function(value) {
var openBrackets=0;
for (var i=0; i<value.length; i++) {
if (value.substr(i, 1)=="(") openBrackets++;
if (value.substr(i, 1)==")") openBrackets--;
}
return openBrackets===0;
};
//Creates a new Section for an expression
worker.createExpression = function(value) {
if (this.properBrackets(value)) {
return new Segment(value);
} else {
return 0;
}
};
worker.graphExpression = function(value, width, height, rangeX, rangeY) {
return new Graph(value, width, height, rangeX, rangeY);
};
return worker;
}());
function simplifyText(event) {
var input = document.getElementById("input").value;
if (XCalc.properBrackets(input)) {
document.getElementById("wrapper").className="";
var timer = setTimeout(function() {
var graph = XCalc.graphExpression(input, 400, 400);
document.getElementById("result").innerHTML = "";
document.getElementById("result").appendChild(graph.getCanvas());
document.getElementById("wrapper").className="solved";
}, 800);
} else {
document.getElementById("result").innerHTML = "<div class='error'>Error: Improperly nested brackets. Remember to only use round brackets and close all opened brackets.</div>";
}
}
window.onload = function() {
document.getElementById("simplify").addEventListener("click", simplifyText);
simplifyText();
};
Note, this won't graph anything unless you have the html/css (i didn't provide that).
Why not? Without it it's a code snippet that doesn't run.
Why not? Without it it's a code snippet that doesn't run.
Oh, well in that case, I will provide the html/css for it... i was thinking since this is a javascript post, it should only be javascript. But here you go:
HTML:
<div id="top"><h1>XCalc.js v.1.8 Demo</h1>
f(x) = <input type="text" value="(x+4)^2*(x-6)+60sinx" id="input" /><input type="button" value="Graph" id="simplify" />
</div>
<div id="wrapper">
<div id="result"></div>
CSS:
body {
background-color:#454545;
color:#FFF;
font-family: sans-serif;
padding:0;
margin:0;
}
#top {
padding:20px;
}
h1 {
font-family: 'Open Sans', sans-serif;
font-size:30px;
margin:0 0 10px 0;
}
input[type="submit"], input[type="button"], a.button {
background-color:#FFF;
color:#000;
padding:5px;
border: 5px solid #FFF;
text-decoration:none;
display:inline-block;
height:40px;
font-size:16px;
font-family:sans-serif;
margin:0 0 0 10px;
}
input[type="submit"]:hover, input[type="button"]:hover, a.button:hover {
border: 5px solid #DDD;
}
input[type="text"] {
display:inline-block;
height:20px;
width: 290px;
padding: 10px;
font-size: inherit;
border: 0;
}
#result {
margin-top:10px;
padding:0 20px;
overflow:hidden;
background-color:#171717;
max-height:0;
-webkit-transition: all 0.3s ease-out;
-moz-transition: all 0.3s ease-out;
-ms-transition: all 0.3s ease-out;
-o-transition: all 0.3s ease-out;
transition: all 0.3s ease-out;
}
.solved #result {
max-height:2000px;
padding:20px;
color:#FFF;
}
.answer {
clear:both;
text-align:center;
}
.group {
padding:5px;
margin:5px;
border:1px solid #FFF;
display:inline-block;
}
.group.operator {
border:0;
}
.final {
color:#FFF;
font-size:60px;
text-align:left;
font-family: 'Open Sans', sans-serif;
}
.error {
zzbackground-color:#6B1010;
padding:10px;
opacity:0.7;
}
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