如何从 JavaScript 中的字符串修剪文件扩展名? [英] How to trim a file extension from a String in JavaScript?

问题描述

例如，假设 x = filename.jpg，我想得到 filename，其中 filename 可以是任何文件名(让我们假设文件名只包含 [a-zA-Z0-9-_] 以简化.).

For example, assuming that x = filename.jpg, I want to get filename, where filename could be any file name (Let's assume the file name only contains [a-zA-Z0-9-_] to simplify.).

我在 x.substring(0, x.indexOf('.jpg'))rel="noreferrer">DZone Snippets，但是 x.substring(0, x.length-4) 会不会表现得更好?因为，length 是一个属性，不做字符检查，而 indexOf() 是一个函数，做字符检查.

I saw x.substring(0, x.indexOf('.jpg')) on DZone Snippets, but wouldn't x.substring(0, x.length-4) perform better? Because, length is a property and doesn't do character checking whereas indexOf() is a function and does character checking.

推荐答案

如果你知道扩展的长度，你可以使用 x.slice(0, -4)(其中 4 是扩展名和点的三个字符).

If you know the length of the extension, you can use x.slice(0, -4) (where 4 is the three characters of the extension and the dot).

如果您不知道长度@John Hartsock regex 将是正确的方法.

If you don't know the length @John Hartsock regex would be the right approach.

如果你不想使用正则表达式，你可以试试这个(性能较差):

If you'd rather not use regular expressions, you can try this (less performant):

filename.split('.').slice(0, -1).join('.')

请注意，它会在没有扩展名的文件上失败.

Note that it will fail on files without extension.

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