javascript - 如何在JavaScript中修剪String中的文件扩展名？(How to trim a file extension from a String in JavaScript?)

Question

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.).(例如，假设x = filename.jpg ，我想获取filename ，其中filename可以是任何文件名（假设文件名仅包含[a-zA-Z0-9-_]以简化。）。)

I saw x.substring(0, x.indexOf('.jpg')) on DZone Snippets , but wouldn't x.substring(0, x.length-4) perform better?(我在DZone Snippets上看到了x.substring(0, x.indexOf('.jpg')) ，但x.substring(0, x.length-4)表现不是更好吗？) Because, length is a property and doesn't do character checking whereas indexOf() is a function and does character checking.(因为， length是一个属性而不进行字符检查，而indexOf()是一个函数并进行字符检查。)   ask by ma11hew28 translate from so