jquery自定义延迟函数

Question

我有三个函数我正在尝试运行,前两个正在做一些异步的东西,需要第三个使用的数据.我希望只有当1和2都完成时才会触发第三个函数.这是一般结构,但最终功能是在1和2结束前开始.

function run() {
    var data1 = {};
    var data2 = {};

    $.when(first(), second()).done(constructData());

    function first() {
        var d = new $.Deferred();

        //do a bunch of stuff async
        data1 = {};

        d.resolve();
    }
    function second() {


        var d = new $.Deferred();

        //do a bunch of stuff async
        data2 = {};
        d.resolve();
    }
    function constructData() {
        //do stuff with data1 and data2
    }

}

答案是不立即调用构造数据

 $.when(first(), second()).done(constructData);

Answer 1

你应该返回promise对象.此行中也有错误:

$.when(first(), second()).done(constructData());

它应该是

$.when(first(), second()).done(constructData); // don't call constructData immediately

所以它们可能是:

function run() {
    var data1 = {};
    var data2 = {};

    $.when(first(), second()).done(constructData);

    function first() {
        return $.Deferred(function() { // <-- see returning Deferred object
            var self = this;

            setTimeout(function() {   // <-- example of some async operation
                data1 = {func: 'first', data: true};
                self.resolve();       // <-- call resolve method once async is done
            }, 2000);
        });
    }
    function second() {
        return $.Deferred(function() {
            var self = this;
            setTimeout(function() {
                data2 = {func: 'second', data: true};
                self.resolve();
            }, 3000);
        });
    }
    function constructData() {
        //do stuff with data1 and data2
        console.log(data1, data2);
    }
}

http://jsfiddle.net/FwXZC/