Javascript 字符串上的方法(性能好)
var str = "It's a long string."var length = 10
console.log( str.slice( 0, length ) ) // "It's a lon"
用正则(match)
var str = "It's a long string."var length = 10
var regExp = new RegExp( "^(.{0," + length + "}).*$" ) // /^(.{0,10}).*$/
console.log( str.match( regExp )[ 1 ] ) // "It's a lon"
用正则(replace)
var str = "It's a long string."var length = 10
var regExp = new RegExp( "^(.{0," + length + "}).*$" ) // /^(.{0,10}).*$/
console.log( str.replace( regExp, "$1" ) ) // "It's a lon"
直接匹配可能不支持,逆序环视不定长度很多语言不支持。建议用捕获括号进行捕获
<script[^>]*>([^<]*)</script>
这样匹配的内容包含前后的<script>标签,不含标签的内容在捕获括号中。