Javascript 如何将变量放入正则表达式匹配中？
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How to put variable in regular expression match?
提问by somebodyelse
I have
我有
var string1 = 'asdgghjajakhakhdsadsafdgawerwweadf';
var string2 = 'a';
string1.match("\/"+string2+"\/g").length;
So with this I want to find the appearance of a, but it does not work. How can I put the variable right?
所以这个我想找到的出现一个，但它不工作。我怎样才能把变量放在正确的位置？
回答by user113716
You need to use the RegExpconstructor instead of a regex literal.
您需要使用RegExp构造函数而不是正则表达式文字。
var string = 'asdgghjjkhkh';
var string2 = 'a';
var regex = new RegExp( string2, 'g' );
string.match(regex);
If you didn't need the global modifier, then you could just pass string2, and .match()will create the regex for you.
如果您不需要全局修饰符，那么您可以只传递string2，并.match()为您创建正则表达式。
string.match( string2 );
回答by Snowcat
Here is another example- //confirm whether a string contains target at its end (both are variables in the function below, e.g. confirm whether str "Abstraction" contains target "action" at the end).
这是另一个例子- //确认一个字符串在其末尾是否包含目标（两者都是下面函数中的变量，例如确认 str "Abstraction" 在末尾是否包含目标 "action"）。
function confirmEnding(string, target) {
let regex = new RegExp(target);
return regex.test(string);
};
