jquery-filter-version

jquery1.0 版本的 filter函数

//筛选出元素
	//1.2.6 如果是Function的话直接grep
	//如果不是Function那么调用multiFilter
	filter: function(t) {
		return this.pushStack(
			t.constructor == Array &&
			jQuery.map(this,function(a){
				for ( var i = 0; i < t.length; i++ )
					if ( jQuery.filter(t[i],[a]).r.length )
						return a;
			}) ||

			t.constructor == Boolean &&
			( t ? this.get() : [] ) ||

			t.constructor == Function &&
			jQuery.grep( this, t ) ||
			//如果是字符串那么直接调用静态方法filter
			jQuery.filter(t,this).r, arguments );
	},

我们再看下静态的filter方法：

filter: function(t,r,not) {
		// Figure out if we're doing regular, or inverse, filtering
		var g = not !== false ? jQuery.grep :
			function(a,f) {return jQuery.grep(a,f,true);};

		while ( t && /^[a-z[({<*:.#]/i.test(t) ) {

			var p = jQuery.parse;//调用parse规则数组

			for ( var i = 0; i < p.length; i++ ) {
				var re = new RegExp( "^" + p[i][0]

					// Look for a string-like sequence
					.replace( 'S', "([a-z*_-][a-z0-9_-]*)" )

					// Look for something (optionally) enclosed with quotes
					.replace( 'Q', " *'?\"?([^'\"]*?)'?\"? *" ), "i" );

				var m = re.exec( t );

				if ( m ) {
					// Re-organize the match
					if ( p[i][1] )//Match: [@value='test'], [@foo]  p[i][1] 为1
 						m = ["", m[1], m[3], m[2], m[4]];

					// Remove what we just matched
					t = t.replace( re, "" );

					break;
				}
			}

			// :not() is a special case that can be optomized by
			// keeping it out of the expression list
			if ( m[1] == ":" && m[2] == "not" )
				r = jQuery.filter(m[3],r,false).r;

			// Otherwise, find the expression to execute
			else {
				var f = jQuery.expr[m[1]];//访问expr 表达式数组
				if ( f.constructor != String )
					f = jQuery.expr[m[1]][m[2]];

				// Build a custom macro to enclose it
				eval("f = function(a,i){" +
					( m[1] == "@" ? "z=jQuery.attr(a,m[3]);" : "" ) +
					"return " + f + "}");

				// Execute it against the current filter
				r = g( r, f );//调用grep函数
			}
		}

		// Return an array of filtered elements (r)
		// and the modified expression string (t)
		return { r: r, t: t };
	}

其实要么就是根据filter筛选 ，要么就是调用grep函数

我们来看看grep函数

grep: function(elems, fn, inv) {
		// 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","i","return " + fn);

		var result = [];

		// Go through the array, only saving the items
		// that pass the validator function
		for ( var i = 0; i < elems.length; i++ )
			if ( !inv && fn(elems[i],i) || inv && !fn(elems[i],i) )
				result.push( elems[i] );

		return result;
	}