how to pass a variable into an regular expression in javascript
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How do you pass a variable to a Regular Expression JavaScript?
I need help to resolve the issue because the code fails due to numLength[0]:
<html>
<body>
<script type="text/javascript">
function xyz(){
var predefLength = "5,5";
var number = "20";
var numLength = predefLength.split(",");
var result = /^[-+]?d{0,numLength[0]}(.d{0,numLength[1]})?$/.test(number);
document.write(result);
}
</script>
</body>
</html>
Any help will appreciated.
Use the RegExp -constructor, like:
var pattern = new RegExp('pattern as a string', 'flags as a string');
Or:
var result = new RegExp('^[-+]?d{0,' + numLength[0] + '}(.d{0,' + numLength[1] + '})?$').test(number);
尝试这个：
<script type="text/javascript">
function xyz(){
var predefLength = "5,5";
var number = "20";
var numLength = predefLength.split(",");
var pattern = new RegExp('^[-+]?d{0,'+numLength[0]+'}(.d{0,'+numLength[1]+'})?$');
var result = pattern.test(number);
document.write(result);
}
</script>
numLength[0] is 5. We can not add evaluation of variable in regular expression. Below code returns true.
var result = /^[-+]?d{0,x}(.d{0,5})?$/.test(number);