多种表单的多个 onsubmit 处理程序

发布于 2024-10-07 12:22:36 字数 867 浏览 5 评论 0原文

我正在编写一段附加的 JavaScript，旨在在提交表单时捕获信息。我需要适应网页上可能有多个表单的情况，其中没有/部分/全部可能已经定义了 onsubmit 处理程序......并且我需要在调用螺栓代码后触发原始处理程序。

我有一个包含 2 个表单的测试用例设置，第一个没有 onsubmit 处理程序，第二个是一个简单的警报框。

我尝试了下面的代码 - 但这似乎将预先存在的处理程序从 form2 复制到 form1：

window.onload=pageinit;

function pageinit()
{
    for (var x=0; x < document.forms.length; x++) {
            var origSubmit=document.forms[x].onsubmit;
            if (typeof origSubmit != 'function') {
                    document.forms[x].onsubmit=dosubmit;
            } else {
                    document.forms[x].onsubmit = function (event) {
                            dosubmit(event);
                            return origSubmit(event);
                    }
            }
    }
}

function dosubmit(ev)
{
  alert('bolt-on invoked from ' + ev.target.name);  
}

有什么想法吗？

TIA

原文

I'm writing a bolt-on bit of javascript which is intended to capture information when a form is submitted. I need to accomodate the scenario where there may be multiple forms on a web page, none/some/all of which may already have onsubmit handlers defined....and I need to fire the original handler after calling the bolt-on code.

I've got a test case setup with 2 forms, the first has no onsubmit handler, the second a simple alertbox.

I tried the code below - but that seemed to copy the pre-existing handler from form2 into form1:

window.onload=pageinit;

function pageinit()
{
    for (var x=0; x < document.forms.length; x++) {
            var origSubmit=document.forms[x].onsubmit;
            if (typeof origSubmit != 'function') {
                    document.forms[x].onsubmit=dosubmit;
            } else {
                    document.forms[x].onsubmit = function (event) {
                            dosubmit(event);
                            return origSubmit(event);
                    }
            }
    }
}

function dosubmit(ev)
{
  alert('bolt-on invoked from ' + ev.target.name);  
}

Any ideas?

TIA

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内心荒芜 2024-10-14 12:22:36

我真的不明白你想要做什么，但你有典型的循环定义中的函数问题：

在任何document.forms[x].onsubmit 函数被调用（显然是在循环完成之后），每个处理程序中的 origSubmit 将指向相同的函数（document.forms[document.forms.length - 1].onsubmit）。您必须“捕获”origSubmit 的值，因为 JavaScript 只有函数作用域，没有块作用域：

 for (var x=0; x < document.forms.length; x++) {
            var origSubmit=document.forms[x].onsubmit;
            if (typeof origSubmit != 'function') {
                    document.forms[x].onsubmit=dosubmit;
            } else {
                    document.forms[x].onsubmit = (function(func) {
                        return function (event) {
                                dosubmit(event);
                                return func(event);
                               }
                    }(origSumbit));
            }
    }

另请参阅 傻瓜式闭包，示例 5

I don't really get what you want to do, but you have the typical function in loop definition problem:

At the the time when any document.forms[x].onsubmit function is called (obviously after the loop finished), origSubmit in each handler will point to the same function (document.forms[document.forms.length - 1].onsubmit). You have to "capture" the value of origSubmit because JavaScript has only function scope, not block scope:

 for (var x=0; x < document.forms.length; x++) {
            var origSubmit=document.forms[x].onsubmit;
            if (typeof origSubmit != 'function') {
                    document.forms[x].onsubmit=dosubmit;
            } else {
                    document.forms[x].onsubmit = (function(func) {
                        return function (event) {
                                dosubmit(event);
                                return func(event);
                               }
                    }(origSumbit));
            }
    }

See also Closures for Dummies, Example 5

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盛夏尉蓝 2024-10-14 12:22:36

我认为问题可能是您的 origSubmit 变量；它对您在那里创建的函数是“封闭的”，但它被 for 循环更改了。

尝试：

function pageinit()
{
    for (var x=0; x < document.forms.length; x++) {
            var origSubmit=document.forms[x].onsubmit;
            if (typeof origSubmit != 'function') {
                    document.forms[x].onsubmit=dosubmit;
            } else {
                    document.forms[x].onsubmit = createSubmitHandler(origSubmit);
            }
    }
}

function dosubmit(ev)
{
  alert('bolt-on invoked from ' + ev.target.name);  
}


function createSubmitHandler(origSubmit) 
{
  return function(event) {
    dosubmit(event);
    return origSubmit(event);
  }
}

I think the issue may be your origSubmit variable; it is 'closed' over the function you create there but it's changed by the for loop.

Try:

function pageinit()
{
    for (var x=0; x < document.forms.length; x++) {
            var origSubmit=document.forms[x].onsubmit;
            if (typeof origSubmit != 'function') {
                    document.forms[x].onsubmit=dosubmit;
            } else {
                    document.forms[x].onsubmit = createSubmitHandler(origSubmit);
            }
    }
}

function dosubmit(ev)
{
  alert('bolt-on invoked from ' + ev.target.name);  
}


function createSubmitHandler(origSubmit) 
{
  return function(event) {
    dosubmit(event);
    return origSubmit(event);
  }
}

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