jQuery equivalent of getting the context of a Canvas

JavascriptJqueryHtmlCanvas

Javascript Problem Overview


I have the following working code:

ctx = document.getElementById("canvas").getContext('2d');

Is there any way to re-write it to use $? Doing this fails:

ctx = $("#canvas").getContext('2d');

Javascript Solutions


Solution 1 - Javascript

Try:

$("#canvas")[0].getContext('2d');

jQuery exposes the actual DOM element in numeric indexes, where you can perform normal JavaScript/DOM functions.

Solution 2 - Javascript

I have also seen that it's often preferred to use .get(0) to reference a jquery target as HTML element:

var myCanvasElem = $("#canvas").get(0);

Perhaps to help avoid any potential null object references since jquery returns null as an object but working with the element from .get(0) may not fail so silently... You can easily check if the canvas was found first before .get(0) like

if( $("#canvas").length ) ctx = $("#canvas").get(0).getContext('2d');
else console.log('Error: Canvas not found with selector #canvas');

Solution 3 - Javascript

try{ 
   ctx = $('#canvas').get(0).getContext('2d');
}catch(e){ 
    console.log('We have encountered an error: ' + e);
}

or...

if( typeof $('#canvas') === 'undefined'){ 
    var canvas = '<canvas id="canvas"><\/canvas>';
    $('body').append(canvas);
}
setTimeout( function(){ ctx = $('#canvas').get(0).getContext('2d'); }, 500);

Using setTimeout is an easy way to ensure you don't try calling the canvas element before it's fully created and registered to the DOM.

Solution 4 - Javascript

The script works before it finds "canvas"

 $(document).ready(function() {
   ctx = $("#canvas");
});

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionClaudiuView Question on Stackoverflow
Solution 1 - JavascriptMattView Answer on Stackoverflow
Solution 2 - JavascriptOG SeanView Answer on Stackoverflow
Solution 3 - JavascriptMistyDawnView Answer on Stackoverflow
Solution 4 - Javascriptалександр лобазовView Answer on Stackoverflow