Regex using javascript to return just numbers

Regular expressions:

var numberPattern = /\d+/g;

'something102asdfkj1948948'.match( numberPattern )

This would return an Array with two elements inside, '102' and '1948948'. Operate as you wish. If it doesn't match any it will return null.

To concatenate them:

'something102asdfkj1948948'.match( numberPattern ).join('')

Assuming you're not dealing with complex decimals, this should suffice I suppose.

You could also strip all the non-digit characters (\D or [^0-9]):

let word_With_Numbers = 'abc123c def4567hij89'
let word_Without_Numbers = word_With_Numbers.replace(/\D/g, '');

console.log(word_Without_Numbers)

For number with decimal fraction and minus sign, I use this snippet:

const NUMERIC_REGEXP = /[-]{0,1}[\d]*[.]{0,1}[\d]+/g;

const numbers = '2.2px 3.1px 4px -7.6px obj.key'.match(NUMERIC_REGEXP)

console.log(numbers); // ["2.2", "3.1", "4", "-7.6"]

Update: - 7/9/2018

Found a tool which allows you to edit regular expression visually: JavaScript Regular Expression Parser & Visualizer.

Update:

Here's another one with which you can even debugger regexp: Online regex tester and debugger.

Update:

Another one: RegExr.

Update:

Regexper and Regex Pal.