jquery - How create follows mouse movement - javascript? -


i'm beginner @ coding. want effec on page - http://tympanus.net/development/animatedheaderbackgrounds

i use scripts site , greensock gsap animation library. can't connect site. html:

  <div id="container">     <canvas id="demo-canvas" width="1400" height="622"></canvas>   </div>

and part of javascript use id elements:

largeheader = document.getelementbyid('container');     largeheader.style.height = height+'px';      canvas = document.getelementbyid('demo-canvas');     canvas.width = width;     canvas.height = height;     ctx = canvas.getcontext('2d');

when use javascript code, error "typeerror: largeheader null".

how correctly use effect ?

is code either

  • a) @ end of <body> element, or
  • b) wrapped in dom ready handler?

otherwise referencing dom element before exists.

this 1 way wrap dom ready (shortcut handler locally scoped $):

jquery(function($){     var largeheader = document.getelementbyid('container');     largeheader.style.height = height+'px';      var canvas = document.getelementbyid('demo-canvas');     canvas.width = width;     canvas.height = height;     var ctx = canvas.getcontext('2d'); });

notes:

  • the traditional dom ready handler $(document).ready(function(){ code }); shortcut nicer
  • also use var declare local variables. otherwise pollute global scope.

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