jQuery中.makeArray()的程式碼閱讀

jquery的makeArray 函數可以將一個類別數組物件轉成數組，官方API解釋和測試範例在這裡（#Convert an array-like object into a true J​​avaScript array.）那麼什麼是類別陣列物件呢？ （ array-like object ） 這是Arrary-Like的定義

Array-Like Object

Either a true J​​avaScript Array or a JavaScript Object that contains a nonnegative integer length property and index properties from 0 up to length - 1. This latter case includes array-like objects commonly encountered in web-based code such as the arguments object and the NodeList object returned by many DOM methods.

When a jQuery API accepts either plain Objects or Array-Like objects, a plain Object with a numeric . will tr​​igger the Array-Like behavior.含有length屬性，且值不為負數，能夠依照下標存取屬性。常見的類別數組物件有aruments，NodeList

// results is for internal usage only result是jquery内部使用的参数，如果不为空则把array并到resuls上
	makeArray: function( array, results ) {
		var ret = results || [];

		if ( array != null ) {
			// The window, strings (and functions) also have 'length'
			// Tweaked logic slightly to handle Blackberry 4.7 RegExp issues #6930
			var type = jQuery.type( array );
			//array没有length属性，或者为string类型，function类型，window类型，或者黑莓中正则对象，黑莓中正则对象也含有length对象，则push到result
			if ( array.length == null || type === "string" || type === "function" || type === "regexp" || jQuery.isWindow( array ) ) {
				push.call( ret, array );
			} else {
				//调用merge把类数组array合并到ret
				jQuery.merge( ret, array );
			}
		}

		return ret;
	}

其中所呼叫的jquery.type 在這裡

jquery.isWindow() 1.7.1是根據是否包含setInterval屬性來判斷的"setInterval" in obj，而以後版面是透過window屬性來判斷的obj == obj.window

isWindow:function(obj){
			return obj && typeof obj === "object" && "setInterval" in obj;
			//1.7.2: return obj != null && obj == obj.window;
		},

呼叫的jQuery.merge(frist,second) 官方解釋在這裡 ，該函數的作用是把第二個數組或類別數組物件合併到第一個中去

merge: function( first, second ) {
		var i = first.length,
			j = 0;
		//length属性为数字，则把second当做数组处理，没有length属性或者不为数字当做含有连续整型的属性对象处理{0:"HK",1:"CA"}
		if ( typeof second.length === "number" ) {
			for ( var l = second.length; j < l; j++ ) {
				first[ i++ ] = second[ j ];
			}

		} else {
			while ( second[j] !== undefined ) { //把不为undefined的都合并到first中
				first[ i++ ] = second[ j++ ];
			}
		}

		first.length = i; //修正length属性，fisrt可能不为真正的数组类型

		return first;
	},

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