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JavaScript Object.create and IE8

I am developing software for SharePoint 2013. Part of this includes overriding the preview of a SharePoint file (filepreview.debug.js becomes myfilepreview.debug.js). However, we ran into problems with IE8. Everything works fine in IE9.

The error that occurred in IE8 causes an error on any site that you visit in the site collection to which our custom function is activated: "The object does not support this property or method"

After Object.create some research on this error, it looks like IE8 just doesn't support Object.create . This Mozilla developer post seems to support this theory. I was more eager to believe this when the problem was solved by adding this polyfill code before the line that generated the error:

 if (typeof Object.create !== 'function') { Object.create = function (o) { function F() { } F.prototype = o; return new F(); }; }

I suppose it would be reasonable that it works because it mimics the functionality of Object.create, which is supposedly not supported in IE8.

However, this is confusing because the javascript JavaScript viewer works fine. Their javascript also uses Object.create. Even the stranger section of code that threw the error in our javascript was not even our code - this is SharePoint. All javascript code before this actually matches SharePoint, with the exception of a few lines.

Here's the default value, down to the corresponding line:

 function $_global_filepreview() { RegisterSod("mediaplayer.js", "_layouts/15/mediaplayer.js"); RegisterSod("sp.publishing.resources.resx", "/_layouts/15/ScriptResx.ashx?name=sp.publishing.resources&culture=" + STSHtmlEncode(Strings.STS.L_CurrentUICulture_Name)); RegisterSodDep("mediaplayer.js", "sp.publishing.resources.resx"); previewBase = (function() { ULS7RK: ; var filePreviewUniqueId = 0; return { init: function(ctxT, listItem, extension) { this.fpId = ++filePreviewUniqueId; this.fpDomId = "FilePreviewID-" + String(this.fpId); this.fpCtx = ctxT; this.fpExtension = extension; this.fpListItem = listItem; }, getHtml: function() { ULS7RK: ; return ['<div class="js-filePreview-containingElement" id=', StAttrQuote(this.fpDomId), '>', this.getInnerHtml(), '</div>'].join(""); }, getDomId: function() { ULS7RK: ; return this.fpDomId; }, getContainingElement: function() { ULS7RK: ; var containingElement = document.getElementById(this.fpDomId); Sys.Debug.assert(m$.isElement(containingElement), "Containing element has not been rendered yet."); return containingElement; }, canRender: function() { ULS7RK: ; return true; }, getLoadingIndicatorHtml: function(customStyle) { if (m$.isUndefined(customStyle)) { customStyle = ""; } return ['<div class="js-filePreview-loading-image" style="width:', this.getWidth(), 'px; height:', this.getHeight(), 'px; line-height:', this.getHeight(), 'px; text-align:center; vertical-align:middle; display: inline-block; ' + customStyle + '">', '<img src="', "/_layouts/15/images/gears_anv4.gif", '" />', '</div>'].join(""); }, hideLoadingIndicator: function() { ULS7RK: ; var containingElement = document.getElementById(this.fpDomId); ((m$(containingElement)).find("div.js-filePreview-loading-image")).css({ display: "none" }); }, getInnerHtml: function() { ULS7RK: ; return ""; }, getWidth: function() { ULS7RK: ; return null; }, getHeight: function() { ULS7RK: ; return null; }, onPostRender: function() { }, onVisible: function() { }, onHidden: function() { } }; })(); //**This is where the "fix" was added originally** blankPreview = Object.create(previewBase); <--- error is thrown here

The only difference between Java javscript (above) and ours (up to this point) is that we deleted these two lines from the very beginning, although adding them did not solve the problem:

 RegisterSod("sp.publishing.resources.resx", "/_layouts/15/ScriptResx.ashx?name=sp.publishing.resources&culture=" + STSHtmlEncode(Strings.STS.L_CurrentUICulture_Name)); RegisterSodDep("mediaplayer.js", "sp.publishing.resources.resx");

So my question is: why am I getting this error that Object.create is not supported in IE8, while other uses of the same exact function in the default javascript work without problems?

EDIT: A user in another forum suggested trying to register my script through sod. I added this to my code without effect:

 RegisterSod("MyFilepreview.debug.js", "_layouts/15/MyFilepreview.debug.js");
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2 answers

Try debugging in IE and place breakpoints in the default SharePoint JavaScript file. Are you sure that Object.create instances in JavaScript are actually deleted by default?

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They do not use Object.create with the corresponding arguments.

They use Object.create({name:value}) when it should be Object.create({name:{value:value}}) .

That way, they probably defined their own Object.create , and their code is used after yours, so you already have your Object.create installed when their code works, and they probably check for existence just like and you, and suggest its version, which is when in fact it is yours.

So, check the definition of Object.create in your code and check the script execution order.

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