javascript - 在没有额外标志的情况下解决 JavaScript 缺少 goto 的问题

Question

在这种情况下，我如何模拟 goto 编程结构？

$.fn.hierarchy = function(info, ret) {
    if (info.constructor !== Object) {
        info = {children: info};
        goto label1; // Illegal JavaScript
    }

    if (!info.children) {
        info.children = [];
        goto label2; // Illegal JavaScript
    }

    label1:
    if (info.children.constructor !== Array)
        info.children = [info.children];

    label2:
    /*
    // Forget this code. It's irrelevant to my specific problem
    // (which is that JS doens't allow non-nested conditionals)
    //  and caused much confusion.
    if (!info.tagc)
        info.tagc = info.tag || 'div';
    */

我知道我可以将这些 goto 中的 ONE 作为 else 子句实现:

$.fn.hierarchy = function(info, ret) {
    if (info.constructor !== Object) {
        info = {children: info};
        //goto label1;
    }

    else if (!info.children) {
        info.children = [];
        goto label2; // Illegal JavaScript
    }

    //label1:
    if (info.children.constructor !== Array)
        info.children = [info.children];

    label2:
    /*
    // Forget this code. It's irrelevant to my specific problem
    // (which is that JS doens't allow non-nested conditionals)
    //  and caused much confusion.
    if (!info.tagc)
        info.tagc = info.tag || 'div';
    */

或者:

$.fn.hierarchy = function(info, ret) {
    if (info.constructor !== Object) {
        info = {children: info};
        goto label1; // Illegal JavaScript
    }

    if (!info.children) {
        info.children = [];
        //goto label2;
    }

    else {
        label1:
        if (info.children.constructor !== Array)
            info.children = [info.children];
    }

    //label2:
    /*
    // Forget this code. It's irrelevant to my specific problem
    // (which is that JS doens't allow non-nested conditionals)
    //  and caused much confusion.
    if (!info.tagc)
        info.tagc = info.tag || 'div';
    */

但我想要两者 goto。而且，不，我不想要额外的标志。

---

编辑:

@Luis Espinal:您提出的解决方案不起作用。如果 info 是 {children: 'a'}，您的程序无法将 info.children 转换为 [a].

$.fn.hierarchy = function(info, ret) {
    if (info.constructor !== Object) {
        info = {children: info};
        // goto label1; // Illegal JavaScript
        // label1:
        if (info.children.constructor !== Array){
            info.children = [info.children];
        }
    }
    else if (!info.children) {
        info.children = [];
        // goto label2; // Illegal JavaScript
        // label2:
        /*
        // Wrong. This has to be placed outside all of this.
        if (!info.tagc)
        {
            info.tagc = info.tag || 'div';
        }
        */
    }
    /* the following code is missing:

    else {
        // Handles the case when info.constructor === Object
        // from the beginning
        // AND
        // info.children isn't an array
        if (info.children.constructor !== Array)
            info.children = [info.children];
    }
    */

---

编辑:你们中的一些人似乎认为第四个条件与我的问题有关。问题实际上是我无法执行以下操作:

If condition1 Then action1
If !condition1 && condition2 Then action2
If !condition2 && condition3 && regardlessOf(condition1) Then action3

不使用标志(临时 bool 变量)。

基本上，如果 condition1 为真，我不必测试 condition2，如果 condition2 为真，我不需要不必测试 condition3。但是，如果 condition1 && !condition2，我可能必须测试 condition3。

Answer 1

也许将标签更改为函数，然后转到 setTimeout(functionname, 0)

例如，代替:

label1:
    // do something
    goto label2

label2:
    // do something
    goto label1

尝试这样的事情:

function label1 () {
    // do something
    setTimeout(label2, 0);
    return; // may be needed if not at the end of function
}

function label2 () {
    // do something
    setTimeout(label1, 0);
    return; // may be needed if not at the end of function
}

(你必须使用超时，因为第一个 JavaScript 还没有优化尾调用，第二个是因为你不想阻塞浏览器，0 的超时会将你的回调放在事件循环的末尾)