JavaScript indexOf来自搜索字符串的结尾 [英] JavaScript indexOf from end of search string

问题描述

Javascript的 String.indexOf 返回字符串中搜索词的索引。

Javascript's String.indexOf returns the index of the a search term within a string.

它返回从搜索字符串的开头开始首次找到字符串的索引。例如：

It returns the index of where the string is first found, from the beginning of the search string. example:

'abcdefghijklmnopqrstuvwxyz'.indexOf('def') = 3;

但我需要在搜索结束时获取它，例如：

But I need to get it from the end of the search, for example:

'abcdefghijklmnopqrstuvwxyz'.indexOf('def') = 6; //essentially index + searchString.length

这样我就可以 String。 substr 从返回的值中获取该点之后的字符串。

so that I can then String.substr from the returned value to get the string after that point.

推荐答案

我将其排序为简单的功能，但在写完之后，我只是觉得它很简单，很有用，我无法理解为什么它还没有被实现为JavaScript！？

I sorted this with a simple function, but after writing it, I just thought it was that simple, and useful that i couldnt understand why it wasn't already implemented into JavaScript!?

String.prototype.indexOfEnd = function(string) {
    var io = this.indexOf(string);
    return io == -1 ? -1 : io + string.length;
}

将获得所需的结果

'abcdefghijklmnopqrstuvwxyz'.indexOfEnd('def'); //6

EDIT也可能包含lastIndexOf实现

EDIT might aswell include the lastIndexOf implementation too

String.prototype.lastIndexOfEnd = function(string) {
    var io = this.lastIndexOf(string);
    return io == -1 ? -1 : io + string.length;
}

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