Implementation code to determine whether an object is Window_jquery

Let’s get straight to the point.
Let’s look at jQuery’s $.isWindow function first:

Copy the code The code is as follows:

function isWin(obj){
return obj && typeof obj === 'object' && 'setInterval' in obj;
}

The function itself It is very scientific, and it is mainly judged by checking whether the target object has the setInterval attribute.
However, the problem is that in the absence of a convention, it may not be reliable, such as:

Copy code The code is as follows:

var o={xx:'oo'};
o[' setInterval']=true;
console.log( isWin(o) ); // true

The above example adds the setInterval attribute to the object literal, and the fraud is successful.
But in fact Above, any non-null Object can be disguised in this way, such as an array:

Copy code The code is as follows:

var arr=[1,2,3];
arr['setInterval']=true;
console.log( isWin(arr) ); // true

Compared with the above property attribute checking, a more appropriate method is to use the toString function of the object to judge:

Copy code The code is as follows:

function isWin(obj){
return Object.prototype.toString.call(obj)==='[object Window]'
}

The above functions work well in standard browsers, but they also bring new compatibility issues:

Copy code The code is as follows:

// Result in ie6-8
Object.prototype.toString.call(window)==='[ object Window]'; // false
Object.prototype.toString.call(window)==='[object Object]'; // true
// chrome
Object.prototype.toString.call (window)==='[object global]'; // true
// safari
Object.prototype.toString.call(window)==='[object DOMWindow]'; // true

Sure enough, the main problem comes from the evil IEs. Fortunately, there is always a path, which reminds me of a supernatural event in IE:

Copy code The code is as follows:

// The following two lines, believe it or not?
console.log( window= =document ); // true
console.log( document==window ); // false

Writing this, I think the final solution has come out:

Copy code The code is as follows:

function isWin(obj){
return/Window| global/.test({}.toString.call(obj))||obj==obj.document&&obj.document!=obj;
}