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如果我想使用创建一个 jQuery 函数Function.prototype.bind，即需要一个包装函数，this我应该提供哪个值？以下简单的示例似乎不起作用：

// e.g.: $.fn.outerHeight() with argument true gets height including margin

$.fn.marginBoxHeight = $.fn.outerHeight.bind($.fn, true);

$.fnthis在这里争论是错误的选择。如果需要，它应该是什么，以便函数可以访问 jQuery 内部方法？

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1 回答 1

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jQuery.proxy执行柯里化如下：

QUnit.test( "jQuery.proxy", function( assert ) {

    var thisObject = { foo: "bar", method: test };

    // jQuery 1.9 improved currying with `this` object context
    fn = function() {
        assert.equal( Array.prototype.join.call( arguments, "," ), "arg1,arg2,arg3", "args passed" );
        assert.equal( this.foo, "bar", "this-object passed" );
    };
    cb = jQuery.proxy( fn, null, "arg1", "arg2" );
    cb.call( thisObject, "arg3" );
} );


QUnit.test( "jQuery.proxy", function( assert ) {
	assert.expect( 9 );

	var test2, test3, test4, fn, cb,
		test = function() {
			assert.equal( this, thisObject, "Make sure that scope is set properly." );
		},
		thisObject = { foo: "bar", method: test };

	// Make sure normal works
	test.call( thisObject );

	// Basic scoping
	jQuery.proxy( test, thisObject )();

	// Another take on it
	jQuery.proxy( thisObject, "method" )();

	// Make sure it doesn't freak out
	assert.equal( jQuery.proxy( null, thisObject ), undefined, "Make sure no function was returned." );

	// Partial application
	test2 = function( a ) {
		assert.equal( a, "pre-applied", "Ensure arguments can be pre-applied." );
	};
	jQuery.proxy( test2, null, "pre-applied" )();

	// Partial application w/ normal arguments
	test3 = function( a, b ) {
		assert.equal( b, "normal", "Ensure arguments can be pre-applied and passed as usual." );
	};
	jQuery.proxy( test3, null, "pre-applied" )( "normal" );

	// Test old syntax
	test4 = { "meth": function( a ) {
		assert.equal( a, "boom", "Ensure old syntax works." );
	} };
	jQuery.proxy( test4, "meth" )( "boom" );

	// jQuery 1.9 improved currying with `this` object
	fn = function() {
		assert.equal( Array.prototype.join.call( arguments, "," ), "arg1,arg2,arg3", "args passed" );
		assert.equal( this.foo, "bar", "this-object passed" );
	};
	cb = jQuery.proxy( fn, null, "arg1", "arg2" );
	cb.call( thisObject, "arg3" );
} );
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<link rel="stylesheet" href="https://code.jquery.com/qunit/qunit-2.4.0.css">
<script src="https://code.jquery.com/qunit/qunit-2.4.0.js"></script>
<div id="qunit"></div>
<div id="qunit-fixture"></div>

最简单的例子是：

var foo = jQuery.proxy(function(){return this('html:first')}, jQuery)
console.log(foo() )
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

参考

于 2017-09-07T22:14:04.267 回答