Javascript image width and height undefined values -

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i try width , heigh previewframe , set values 100% both when try alert undefined values. here html file:

<html> <head>     <link rel="stylesheet" href="frame.css"> </head> <body> <div id="previewwrapper">     <div id="previewframe">         <img id="previewimage" src="http://i.forbesimg.com/media/lists/companies/google_416x416.jpg">                    </img>     </div> </div> <script src="frame.js"></script> </body>

and here css:

html, body{     margin:0;     background:#ccc; }  #previewwrapper{     margin:44px 0px;     width:100%;     height:calc(100% - 88px); }  #previewframe{     width:100%;     height:100%;     margin-top:44px;     background:#000; }  #previewframe img{     max-width:100%;     max-height:100%;  }

and js:

    function imageinfo() {     var pframe = document.getelementbyid("previewframe");     pframe.setattribute('style', "width: 100%; height: calc(100% - 88px);");     var framewidth = pframe.width;     var frameheigh = pframe.height;     var pimage = document.getelementbyid("previewimage");     var imagewidth = pimage.width;     var imageheigh = pimage.height;     alert('frame size '+framewidth+'px x '+frameheigh+'px'); } window.onload = imageinfo;

first of setattribute method, not object property style. should 

pframe.setattribute('style', "width: 100%; height: calc(100% - 88px);");

the second problem in order read browser-calculated css properties need use getcomputedstyle method:

var pframestyle = window.getcomputedstyle(pframe, null); var framewidth = pframestyle.width; var frameheigh = pframestyle.height;

demo: http://jsfiddle.net/yxz4201q/2/


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