javascript replace函数
定义
replace()函数用于替换字符串.
语法
stringObject.replace(regexp/substr, newSubStr/function)
参数
regexp/substr 正则表达式/字符串
newSubStr/function 替换文本/生成替换文本的函数
示例
var str = "Visit Microsoft!";
var res = str.replace("Microsoft", "W3Schools");
替换字符
假如替换字符newSubStr中包含$符号，它表示什么？
$1、 $2、 ...、$99 与 regexp 中的第1到第99个子表达式相匹配的文本
$& 与 regexp 相匹配的子串
$` 位于匹配子串左侧的文本
$' 位于匹配子串右侧的文本
$$ 直接量符号。
上面$1、$2...中提到的子表达式是什么意思？正则表达式中用小括号包裹起来的表达式.
例如：
/a/ 无子表达式
/[a]/ 无子表达式
/(a)/ 有子表达式(a)
/(a), (b)/ 有子表达式(a)、(b)
示例
name = "Doe, John"; name.replace(/(\w+)\s*, \s*(\w+)/, "$2 $1"); //输出"John Doe"
替换函数
替换函数说明
function(match, p1, p2,..., offset, string)
match 匹配到的字符串
p1, p2... 匹配到的子表达式
offset 匹配到字符串的位置
string 整个字符串
示例
var name = "ace:mm-Abc".replace(/([\:\-\_]+(.))/, function(match, p1, p2, offset, total){
console.log("match:" + _);
console.log("p1:" + separator);
console.log("p2:" + letter);
console.log("offset:" + offset);
console.log("total:"+ total)
return offset ? p2.toUpperCase() : p2;
})
console.log(name)
/*输出
substr::m test.html:43
p1::m
p2:m
offset:3
total:ace:mm-Abc
aceMm-Abc
*/
上面正则表达式中有两个子表达式
p1是子表达式([\:\-\_]+(.))匹配到的内容":m"
p2是子表单是(.)匹配到的内容"m"
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