此代码仿照jquery源码中$.when()的实现

复制代码 代码如下:

function test(i) {

var dfd = $.Deferred();

if(i%2 == 0) {

console.log("resolve " + i);

dfd.resolve();

} else {

console.log("failure " + i);

dfd.reject();

}

return dfd.promise();

}

function call() {

var dfd = $.Deferred();

var remain = 10;

for(var i=0;i< 10;i++){

test(i).done(function() {

if(!(--remain)) {

dfd.resolve();

}

}).fail(function() {

if(!(--remain)) {

dfd.resolve();

}

})

}

return dfd.promise();

}

call().done(function() {

console.log("all finished");

});

输出结果：

复制代码 代码如下:

resolve 0 test.js:4

failure 1 test.js:7

resolve 2 test.js:4

failure 3 test.js:7

resolve 4 test.js:4

failure 5 test.js:7

resolve 6 test.js:4

failure 7 test.js:7

resolve 8 test.js:4

failure 9 test.js:7

all finished