JavaScript String lastIndexOf()用法及代码示例

字符串 lastIndexOf() 方法

lastIndexOf() is method 是一个 String 方法，用于检查给定字符串中是否存在子字符串。它从子字符串所在的字符串返回子字符串的最后一个索引。如果字符串中不存在子字符串 – 则返回 -1。

用法:

    String.lastIndexOf(substring, [offset]);

这里，substring是要搜索的字符串的一部分，并且[offset]是我们要搜索子字符串的特定索引，它是一个可选参数，默认值为 0。

注意： 方法 lastIndexOf()在字符串中向后搜索，参见示例 - 我们传递了偏移量 15，它返回索引 0。

例：

<html>
<head>
<title>JavaScipt Example</title>
</head>

<body>
<script>		
	var str = "Hello friends say Hello";
	
	var substr = "Hello";		
	var index = str.lastIndexOf(substr);
	if(index!=-1)
		document.write(substr + " found at " + index + " position.<br>");
	else
		document.write(substr + " does not exist in the " + str + ".<br>");

	substr = "Hi";
	index = str.lastIndexOf(substr);		
	if(index!=-1)
		document.write(substr + " found at " + index + " position.<br>");
	else
		document.write(substr + " does not exist in the " + str + ".<br>");
	
	//searching from a specific index
	substr = "Hello";
	index = str.lastIndexOf(substr,10);		
	if(index!=-1)
		document.write(substr + " found at " + index + " position.<br>");
	else
		document.write(substr + " does not exist in the " + str + ".<br>");		

	substr = "friends";
	index = str.lastIndexOf(substr,15);		
	if(index!=-1)
		document.write(substr + " found at " + index + " position.<br>");
	else
		document.write(substr + " does not exist in the " + str + ".<br>");					
</script>
</body>
</html>

输出

Hello found at 18 position.
Hi does not exist in the Hello friends say Hello.
Hello found at 0 position.
friends found at 6 position.

相关用法

注：本文由纯净天空筛选整理自 String lastIndexOf() Method with Example in JavaScript。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。