Determines whether the object is a window.

This is a very interesting question. Let's start with object. Prototype. tostring to see if it can be solved.

<Br/> alert (object. Prototype. tostring. Call (window) <br/>

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The results are varied:

• [Object object] IE6
• [Object object] IE8
• [Object window] ie9
• [Object window] firefox3.6
• [Object window] opera10
• [Object domwindow] safai4.04
• [Object Global] chrome5.0.3.22

Let's take a look at how to determine whether a famous person has a property called setinterval. It seems that the generalization function is not rigorous, but it cannot be rigorous, because in IE, it cannot determine whether the generalized function is a function, object. prototype. tostring. [Object] is displayed for all calls, and there is no name attribute. Because it is too easy to copy, discard it.

In desperation, check the attributes one by one to see what special attributes are available. Finally, we found that there is a window attribute with the same name, which references itself infinitely. This is still a problem in IE.

<Br/> alert (window === window. Window) <br/>

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IE will pop up false, and other browsers will pop up true. However, all browsers are unified as follows:

<Br/> alert (window = Window. Window) <br/>

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Are there any rigorous judgments? Do not forget that window references itself in an infinite loop. It should be said that it references the previous one. Therefore, we can:

<Br/> alert (window. Window === window. Window. Window) <br/>

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Finally, it is concluded that:

VaR iswindow = function (OBJ) {return obj. Window = obj. Window. Window}
 

==================================== Gorgeous demarcation line ====================== ========

Thanks for the inspiration provided by ivony!

<Br/> var Dom ={}; <br/> Dom. iswindow = function (OBJ) {<br/> If (! OBJ |! OBJ. Window |! Obj.doc ument) <br/> return false; <br/> var expando = "dom" + (new date-0) // generate a random variable name <br/> var Doc = obj.doc ument; <br/> // The Global parsing code, the eval of IE is only valid for the original scope <br/> // For details, see the http://www.javaeye.com/topic/519098 <br/> // In addition, Eval and with are things to be prohibited under the strict HTML5 mode, discard it! <Br/> try {<br/> var JS = Doc. createelement ("script"); <br/> var head = Doc. getelementsbytagname ("head") [0]; <br/> head. insertbefore (JS, head. firstchild); <br/> Js. TEXT = expando + "={};" <br/> head. removechild (JS); <br/> var ret = (Doc. parentwindow | Doc. defaultview) [expando] === OBJ [expando]; <br/> OBJ [expando] = void 0; <br/>} catch (E) {<br/> return false; <br/>}< br/> return ret; <br/>}< br/> var test1 = {}; <br/> test1.window = test1; <br/> test1.document = Document; <br/> alert (Dom. iswindow (test1) </P> <p> var Test2 ={}; <br/> test2.window = Window; <br/> test2.document = document; <br/> alert (Dom. iswindow (Test2) </P> <p> alert (Dom. iswindow (window) <br/>

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2011.10.4 update

</P> <p> var Dom ={}, <br/> windowstring = {<br/> "[Object window]": 1, <br/> "[object domwindow]": 1, <br/> "[object Global]": 1 <br/> }; <br/> // by situ zhengmei http://www.cnblogs.com/rubylouvre/ <br/> Dom. iswindow = function (OBJ) {<br/> If (! OBJ | typeof OBJ! = "Object") // must be an object <br/> return false; <br/> If (windowstring [windowstring. tostring. call (OBJ)]) <br/> return true; <br/> return OBJ = obj.doc ument & obj.doc ument! = OBJ <br/>}< br/> // test code <br/> var test1 ={}; <br/> test1.window = test1; <br/> test1.document = Document; <br/> alert (Dom. iswindow (test1) // false </P> <p> var Test2 ={}; <br/> test2.window = Window; <br/> test2.document = document; <br/> alert (Dom. iswindow (Test2) // false </P> <p> alert (Dom. iswindow (window) // true <br/> var IFRAME = document. createelement ("iframe"); <br/> document. body. appendchild (IFRAME); <br/> var iwin = IFRAME. contentWindow | IFRAME. contentdocument. parentwindow; <br/> alert (Dom. iswindow (iwin); // true <br/> document. body. removechild (IFRAME); </P> <p> var WG = {document :{}}, wgdoc = wg.doc ument; <br/> WG. window = WG; <br/> wgdoc. createelement = function () {return WG ;}; <br/> wgdoc. getelementsbytagname = function () {return [WG] ;}; <br/> wgdoc. parentwindow = WG; <br/> WG. insertbefore = function () {}; <br/> WG. firstchild = WG. firstchild; <br/> WG. removechild = function () {}; <br/> alert (Dom. iswindow (WG); // false </P> <p>

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