javascript JS 获取倒数第二个索引
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JS Get Second To Last Index Of
提问by Nicolas
I am trying to figure out how to get the second to last index of a character in a string.
我想弄清楚如何获取字符串中字符的倒数第二个索引。
For example, I have a string like so:
例如，我有一个像这样的字符串：
http://www.example.com/website/projects/2
I currently get the number 2by using
我目前2使用
$(location).attr('href').substring($(location).attr('href').lastIndexOf('/')+1);
$(location).attr('href').substring($(location).attr('href').lastIndexOf('/')+1);
But what if I want to get the word projects?
但是如果我想得到这个词projects呢？
Can anybody help me out with this? Thanks in advance!
有人可以帮我解决这个问题吗？提前致谢！
回答by antyrat
回答by Rahul R.
Without using split, and a one liner to get the 2nd last index:
不使用 split 和 one liner 来获得倒数第二个索引：
var secondLastIndex = url.lastIndexOf('/', url.lastIndexOf('/')-1)
The pattern can be used to go further:
该模式可用于更进一步：
var thirdLastIndex = url.lastIndexOf('/', (url.lastIndexOf('/', url.lastIndexOf('/')-1) -1))
Thanks to @Felix Kling.
感谢@Felix Kling。
A utility function:
效用函数：
String.prototype.nthLastIndexOf = function(searchString, n){
var url = this;
if(url === null) {
return -1;
}
if(!n || isNaN(n) || n <= 1){
return url.lastIndexOf(searchString);
}
n--;
return url.lastIndexOf(searchString, url.nthLastIndexOf(searchString, n) - 1);
}
Which can be used same as lastIndexOf:
可以和 lastIndexOf 一样使用：
url.nthLastIndexOf('/', 2);
url.nthLastIndexOf('/', 3);
url.nthLastIndexOf('/');
