Question

这是我的问题：

我的主要功能：

const mainFunction = () => {
    const reports = JSON.parse($sessionStorage.datas);
    // reports contains array of objects.
    // consider i have two objects inside one array, so the loop will execute two times now
    reports.forEach((item) => {
        this.openReport(item);
    });
};
mainFunction();

openReport函数：

this.openReport = (report)  => {
    console.log('openReport working');
    // some async functions will be here
    // ajax calls
    this.openTab(report);
};

openTab函数：

this.openTab = (report) => {
    console.log('handleOpenTab function working');
}

输出：

// Now i have two objects, so forEach works two times.
'openReport working'
'openReport working'

'handleOpenTab function working'
'handleOpenTab function working'

我的预期输出：

'openReport working'
'handleOpenTab function working'

'openReport working'
'handleOpenTab function working'

如何实现？我无法在我的forEach函数中使用异步等待，因为使用的是旧节点版本。

如果有可能使用async / await解决此问题，我将尝试升级我的节点版本。

Answer 1

使用诺言，可能看起来像这样：

this.openReport = (report) => {
    console.log('openReport working');
    // some async functions will be here
    // ajax calls
    return new Promise(function(resolve, reject) {
        ajaxCall('url', resolve); // reject as necessary!
    }).then(answer => {
        this.openTab(report);
        return answer;
    });
};

const mainFunction = () => {
    const reports = JSON.parse($sessionStorage.datas);
    // reports contains array of objects.

    function getNextReport(index) {
        if (index >= reports.length) return Promise.resolve();
        let item = reports[index];
        return this.openReport(item).then(function(answer) {
            // do something with answer
            return getNextReport(index+1);
        });
    }

    return getNextReport(0);
};

使异步功能以同步方式运行-Javascript

1 个答案: