如何从 Javascript FileReader base64 字符串中去除类型?

2022-01-21 00:00:00 base64 javascript strip

我的 Javascript 中有以下代码:

I've got the following code in my Javascript:

var reader = new FileReader();
reader.onloadend = function () {
    alert(reader.result);
};

这显示了以下数据:

 data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAAAAABX3VL4AAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB3RJTUUH3gYSDCUgSze0AAAAAA5JREFUCNdjrGJgYmAAAAJ0AH4SDHVIAAAAAElFTkSuQmCC

问题是我只想要逗号后面的部分.我尝试从 reader.result.value、reader.result.valueOf() 和其他一些组合中获取它，但找不到正确的组合来获取 base64从逗号后开始的字符串.所以第二个想法是简单地去掉逗号和之前的所有内容，但我有点不确定该怎么做.

The thing is that I only want the part after the comma. I tried getting it from reader.result.value, reader.result.valueOf() and some other combinations, but can't find the correct one to JUST get the base64 string starting from after the comma. So a second idea is to simply strip off the comma and all that is before that, but I'm kind of unsure how to do that.

有人知道如何完成这项工作吗?欢迎所有提示！

Would anybody have any idea how to get this done? All tips are welcome!

推荐答案

以下函数将达到你想要的结果:

The following functions will achieve your desired result:

var base64result = reader.result.split(',')[1];

这会将字符串拆分为字符串数组，其中第一项(索引 0)包含 data:image/png;base64，第二项(索引 1)包含 base64 编码数据.

This splits the string into an array of strings with the first item (index 0) containing data:image/png;base64 and the second item (index 1) containing the base64 encoded data.

另一种解决方案是找到逗号的索引，然后简单地将逗号之前和包括逗号在内的所有内容都删除:

Another solution is to find the index of the comma and then simply cut off everything before and including the comma: 

var base64result = reader.result.substr(reader.result.indexOf(',') + 1);

参见 JSFiddle.

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