jquery之map函数解析

jquery1.0源码解读

filter函数

1.0源码:

map: function(elems, fn) {
	// If a string is passed in for the function, make a function
	// for it (a handy shortcut)
	if ( fn.constructor == String )
		fn = new Function("a","return " + fn);

	var result = [];//初始化一个空数组

	// Go through the array, translating each of the items to their
	// new value (or values).
	for ( var i = 0; i < elems.length; i++ ) {
		var val = fn(elems[i],i);//调用参数fn 函数 返回fn中的新结果

		//跟grep的函数区别就在于返回的是函数中新的返回值
		//这就是映射
		//而不是返回满足函数条件的旧元素
		if ( val !== null && val != undefined ) {
			if ( val.constructor != Array ) val = [val];
			result = jQuery.merge( result, val );//合并
		}
	}

	return result;
}