JavaScript's power lies in its ability to create dynamic regular expressions

Currently, I am working on code that requires matching a specific number of digits after a decimal point. Here is what I have so far:

var input = getValueFromUser();
var count = getCount();
var x = Number(input.toString().match(/^\d+(?:\.\d{0,1})?/));
alert(x);

The current approach only captures the first digit after the decimal point. However, I would like to dynamically update the regex to match the number based on the value stored in count. I attempted the following modification:

var pattern = '/^\d+(?:\.\d{0,' + count + '})?/';
var x = Number(input.toString().match(pattern));

Unfortunately, this adjustment always results in 0 for x.

Answer №1

If you need to utilize dynamically constructed patterns, the Regexp object is essential:

To create a regular expression with a variable count:
var pattern = new RegExp('^\\d+(?:\\.\\d{0,' + num + '})?');

Answer №2

Here is a solution for you.

let pattern = '^\\d+(?:\\.\\d{0,' + '3' + '})?',
    regex = new RegExp(pattern),
    value = Number(input.toString().match(regex));

Answer №3

pattern: new RegExp(`^[a-zA-Z0-9]{0,${maxLength}}$`)

It's effective in my case

Answer №4

const extraterrestrial = 'ajay' + ' $%';
const reveal=new RegExp(`${extraterrestrial}`)

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