如何在递归方法中进行同步调用？

Question

我正在尝试运行一个呼叫并停止递归 function 在完成另一个 function 之前继续运行。

我尝试使用 promise 但我只是不明白在.then()部分中放入什么作为递归调用。

    const htmlString = '<table><tr><td>Bah</td><td>Pooh</td></tr></table>';
    const fragment = 
    document.createRange().createContextualFragment(htmlString);

    function walkTheDOM(node, func) {
        func(node);
        node = node.firstChild;
        while (node) {
            walkTheDOM(node, func);
            node = node.nextSibling;
        }
    }

    function asynchronousCallWantingtoMakeSynchronous() {
       return new Promise((resolve, reject) => {
           setTimeout(function() {
       return resolve ( console.log("should come before another recursive call"))
           }, 0)
       });
    }

    walkTheDOM(fragment, function(node) {
        console.log(node)
        asynchronousCallWantingtoMakeSynchronous.then(function(){

        })
    })

这实际上打印出什么：

    <table>...</table>
    <tr>...</tr>
    <td>Bah</td>
    "Bah"
    <td>Pooh</td>
    "Pooh"
    "should come before Pooh"

我真正想要的是：

    <table>...</table>
    "should come before another recursive call"
    <tr>...</tr>
    "should come before another recursive call"
    <td>Bah</td>
    "should come before another recursive call"
    "Bah"
    "should come before another recursive call"
    <td>Pooh</td>
    "should come before another recursive call"
    "Pooh"
    "should come before another recursive call"

请记住，setTimeout 只是一个示例，我只是想让异步调用同步。

Answer 1

没有办法使异步 function 同步。 但是您可以使用Promises或async-await让它感觉更像这样。 你可以使用这些来打断你的电话

 const htmlString = '<table><tr><td>Bah</td><td>Pooh</td></tr></table>'; const fragment = document.createRange().createContextualFragment(htmlString); async function asyncWalkTheDOM(node, func, intersperse) { func(node); node = node.firstChild; while (node) { await intersperse(node) asyncWalkTheDOM(node, func, intersperse); node = node.nextSibling; } } async function asynchronousCall(node) { return new Promise(function (res, rej) { setTimeout(function() { console.log("should come before another recursive call") res(node) }, 0) }) } asyncWalkTheDOM(fragment, function(node) { console.log(node.nodeName) }, asynchronousCall)