使用javascript清除/重置formData（） [英] clear/reset formData() using javascript

问题描述

我在下面使用formData，并传递结果。但是，如果用户不止一次重复数据，则会被复制。所以我必须在添加任何值之前清除/重置formData。

I use formData below, and pass the results. But data is duplicated if the user does it more than once. So I have to clear/reset the formData before adding any value.

我可以像f.name =''一样一对一地做，我有很多键。有没有更好的方法可以解决问题？

I can do it one-by-one like f.name = '', I have tons of keys. Is there any better way to solve the problem?

$('input').change(function(){
// Create a new formdata but at first have to clear/reset it
var fd = new FormData();
var f = $.canvasResize('dataURLtoBlob', data);
f.name = file.name;
fd.append($('#area input').attr('name'), f);
})

推荐答案

@ gurvinder372的答案不会从您的FormData中删除键，而是将其设置为空字符串，它不是服务器端。

例如，在php中， if（isset（$ _ POST [ yourKey]））

@gurvinder372's answer won't remove your keys from your FormData, it will just set it to an empty string, which is not the same server side.
E.g, in php, if ( isset($_POST["yourKey"]) ) will still evaluate to true.

不幸的是，最好的跨浏览器方法是根据您的情况创建一个新的FormData对象。

The best crossbrowser way is unfortunately to create a new FormData object in your situation.

fd = new FormData();

---

另一种可能性，尽管目前仅受 Chrome> = 50 和 Firefox> = 39 ，将使用 formData.set（） 方法。

该值将替换为

---

An other possibility, though it's currently only supported by Chrome>=50 and Firefox>=39, is to use the formData.set() method.
This will replace the value at set key, or append it if no such key is there.

formData.set('yourKey', yourValue);

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现在回答问题的标题，在 Chrome> = 50 和 Firefox> = 44 ，则可以使用 用于.. of formData.keys（） 和您的FormData对象的删除 方法：

---

Now to answer the title of the question, in Chrome>=50 and Firefox>=44, you can use for .. of formData.keys() and delete methods of your FormData Object :

var formData = new FormData();
formData.append('yourKey', yourValue);

for (var key of formData.keys()) {
    // here you can add filtering conditions
    formData.delete(key)
    });

，甚至使用 forEach 方法（显然

var formData = new FormData();
formData.append('yourKey', yourValue);

formData.forEach(function(val, key, fD){
    // here you can add filtering conditions
    formData.delete(key)
    });

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