问在javascript/jquery中按顺序解析promise

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function home() {
    var home = document.getElementById('home');
    // return the promise, so you can chain it
    return html2canvas(home).then(function(canvas) {
        home.appendChild(canvas);
        var basic = canvas.toDataURL();
        var item = {};
        item["image"] = basic;
        item["width"] = 595;
        data_1.push(item);
    });
}

function options() {
    // create a promise to chain in .each
    var ret = $.when();
    $('.tour_options_table_data_info').each(function(index, element) {
        // chain the promises
        ret = ret.then(function() {
            html2canvas(element).then(function(canvas) {
                element.appendChild(canvas);
                elem = canvas.toDataURL();
                var item = {};
                item["image"] = elem;
                item["width"] = 595;
                data_1.push(item);
            });
        });
    });
    // return the last promise
    return ret;
}

function inclusions() {
    // create a promise to chain in .each
    var ret = $.when();
    $('.inc-main1,.inc-main2,.inc-main3').each(function(index, element) {
        // chain the promises
        ret = ret.then(function() {
            html2canvas(element).then(function(canvas) {
                element.appendChild(canvas);
                elem = canvas.toDataURL();
                var item = {};
                item["image"] = elem;
                item["width"] = 595;
                data_1.push(item);
            });
        });
    });
    // return the last promise
    return ret;
}
home().then(options).then(inclusions).then(() => {
    // data_1 has all the "items" in the order you need
    // i.e. home item, n * options items, m * inclusions items
});