此代碼仿照jquery源碼中$.when()的實現

復制代碼 代碼如下:

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");
});

輸出結果：

復制代碼 代碼如下:

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