来自搜索字符串末尾的 JavaScript indexOf
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JavaScript indexOf from end of search string
提问by rorypicko
Javascript's String.indexOfreturns the index of the a search term within a string.
JavascriptString.indexOf返回字符串中搜索词的索引。
It returns the index of where the string is first found, from the beginning of the search string. example:
它从搜索字符串的开头返回第一次找到字符串的位置的索引。例子：
'abcdefghijklmnopqrstuvwxyz'.indexOf('def') = 3;
But I need to get it from the end of the search, for example:
但是我需要从搜索的末尾获取它，例如：
'abcdefghijklmnopqrstuvwxyz'.indexOf('def') = 6; //essentially index + searchString.length
so that I can then String.substrfrom the returned value to get the string after that point.
这样我就可以String.substr从返回的值中获取该点之后的字符串。
回答by rorypicko
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!?
我用一个简单的函数对它进行了排序，但是在编写它之后，我只是认为它是如此简单和有用，以至于我无法理解为什么它尚未实现到 JavaScript 中！？
String.prototype.indexOfEnd = function(string) {
var io = this.indexOf(string);
return io == -1 ? -1 : io + string.length;
}
which will have the desired result
这将有想要的结果
'abcdefghijklmnopqrstuvwxyz'.indexOfEnd('def'); //6
EDIT might aswell include the lastIndexOf implementation too
编辑也可能包括 lastIndexOf 实现
String.prototype.lastIndexOfEnd = function(string) {
var io = this.lastIndexOf(string);
return io == -1 ? -1 : io + string.length;
}
回答by Mark Schultheiss
var findStr = "def";
var searchString = 'abcdefghijklmnopqrstuvwxyz';
var endOf = -1;
endOf = searchString.lastIndexOf(findStr) > 0 ? searchString.lastIndexOf(findStr) + findStr.length : endOf;
alert(endOf);
Alerts -1 if not found
如果未找到，警报 -1
Note returns 23 if you have this string:
如果您有此字符串，请注意返回 23：
var searchString = 'abcdefghijklmnopqrstdefuvwxyz';
As a function:
作为一个函数：
function endofstring (searchStr,findStr){
return searchStr.lastIndexOf(findStr) > 0 ? searchStr.lastIndexOf(findStr) + findStr.length : -1;
}
endofstring(searchString,"def");
