使异步函数同步运行 - Javascript

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'

如何做到这一点？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。

如果可以使用 async/await 来解决这个问题，我会尝试升级我的节点版本。

Answer 1

使用 Promise，它可能看起来像这样：

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);
};