如何简单地在正则表达式替换语句中传递变量？

Question

我有一个变量字符串短语，我想用变量中的内容修剪字符串的开头，或者没有空格。

var fullphrase = "how can I trim this phrase?";
var cutthis = "how Can i";
var result = fullphrase.replace("/^cutthis ?/i","");

我希望结果是=“修剪这个短语？”

我该如何做到这一点？

Answer 1

为什么不将变量传递给replace参数？

var fullphrase = "how can I trim this phrase?";
var cutthis = "how Can i";
var result = fullphrase.replace(new RegExp("^" + cutthis + " ?", 'i'),"");

Answer 2

var fullphrase = "how can I trim this phrase?";
var cutthis = "how Can i";
var result = fullphrase.replace(new RegExp('^' + cutthis + ' ?', 'i') ,"");

Answer 3

要动态构建模式，请使用RegExp对象：

var fullphrase = "how can I trim this phrase?";
var cutthis = "how Can i";
var pattern = "^" + cutthis + " ?";
var re = new RegExp(pattern, "i");
var result = fullphrase.replace(re,"");
console.log(result);

查看JSBin demo此操作。