Strip all non-numeric characters from string in JavaScript

Question

Consider a non-DOM scenario where you'd want to remove all non-numeric characters from a string using JavaScript/ECMAScript. Any characters that are in range 0 - 9 should be kept.

var myString = 'abc123.8<blah>';

//desired output is 1238

How would you achieve this in plain JavaScript? Please remember this is a non-DOM scenario, so jQuery and other solutions involving browser and keypress events aren't suitable.

Magistrate

Answer 1

Use the string's .replace method with a regex of \D, which is a shorthand character class that matches all non-digits:

myString = myString.replace(/\D/g,'');

Gynaeco

Thanks csj; anyplace to find more info on \D ? – Magistrate

This is my default regex reference: regular-expressions.info/reference.html The built-in character classes each have built-in complements. \d \D (digits versus everything but digits) \w \W (word charcters versus everything but word characters) \s \S (whitespace versus everything but whitespace) – Gynaeco

Just to be clear, here is the syntax for replace: w3schools.com/jsref/jsref_obj_regexp.asp because the forward slashes and the "g" are part of that command, not part of the RegEx. – Barina

does replace work with this exact syntax in all browsers? seems like I remember getting an object has no method 'replace' in an older version of IE when using this with text I grabbed with jQuery... or something like that. – Induplicate

@Induplicate I have no idea what has been supported in past or current browsers. The question specified a non-DOM context, so it's likely that the poster was scripting in a non web browser environment. – Gynaeco

Great tool to test regular expression online (It's not mine :)). regex101.com – Bonnybonnyclabber

i tried following but nothing worked "this.value = this.value.replace(eval(!/^[A-Za-z\d.#-,]$/),'')" "this.value = this.value.replace(eval(/^[A-Za-z\d.#-,]$/),'')" "this.value = this.value.replace(eval(specialCharRegex),'')" what should i do? – Hawkins

You can use String(myString).replace(/\D/g,'') in case they pass only a number this code won't throw an error. – Shaner

this works fine for positive integers but goodbye negative numbers. – Throne

This turns 1.2 into 12 – Skippie

@Throne fair enough, but the OP did eventually edit their question to indicate that they were seeking to preserve the digits themselves. 0-9 – Gynaeco

@Skippie The OP's example specifically shows a period being stripped away. – Gynaeco

Answer 2

If you need this to leave the dot for float numbers, use this

var s = "-12345.50 €".replace(/[^\d.-]/g, ''); // gives "-12345.50"

Klos

Any regexp experts? How to make this allow only a single dot (very relevant with numbers). Thanks! – Vulvitis

what do you mean? give input and output example – Klos

I mean, it currently accepts for example "1..56" and "1.5.28", right? Is it possible to make it accept only numbers with a single dot, such as "1.56"? – Vulvitis

use https://mcmap.net/q/54381/-regex-to-check-whether-a-string-contains-only-numbers-duplicate to test it like this: new RegExp(/^-?\d+\.?\d*$/).test("1.5.28") – Klos

Is that possible to change all , by . in your regex? In some countries, the comma is used as a separator instead of the point. :) – Batten

@Batten it is, but be aware, in such cases there is possibilty they are both there (Eg. 1,000,000.5) - so you should rather do .replace(/",","."/g) first :) – Gullett

@Klos Whats with the "-" in the regexp? – Gullett

Not good: "aaa 2.9px of bbb.".replace(/[^\d.-]/g, '') → 2.9. Should strip any String which might surround a Number.. – Dipietro

Great test! my first idea is [^\d.-]+[^\d]+ should work in this case – Klos

@Klos you saved my life, thanks for handling -(negative) number case :) – Ethylethylate

@Vulvitis perhaps: parseFloat("-1234.5.50 €".replace(/[^\d.-]/g, '')) – Apul

Great answer, if you want a numeric field you mean any number event floats :) – Eventempered

Answer 3

Use a regular expression, if your script implementation supports them. Something like:

myString.replace(/[^0-9]/g, '');

Homicidal

For some reason this way seems much more readable than [^\d]. – Menke

whats the g for after the regex delimiter?? – Platonism

@NativeCoder #12994129 – Guthrie

will not work for float/decimal values for example, "7.6$" will return 76 – Find

like @SikandarTariq mentioned but also negative values. – Throne

Answer 4

You can use a RegExp to replace all the non-digit characters:

var myString = 'abc123.8<blah>';
myString = myString.replace(/[^\d]/g, ''); // 1238

Holler

Answer 5

Something along the lines of:

yourString = yourString.replace ( /[^0-9]/g, '' );

Subset

Not exactly an answer to the original question, but a version to handle the decimal point: yourString = yourString.replace ( /[^0-9.]/g, '' ); – Antimagnetic

Late to the party but also need dash and comma. In certain regions decimal is done with a comma: replace(/[^0-9.,-]/g, '' – Hallucinogen

Answer 6

Short function to remove all non-numeric characters but keep the decimal (and return the number):

parseNum = str => +str.replace(/[^.\d]/g, '');
let str = 'a1b2c.d3e';
console.log(parseNum(str));

Candelariacandelario

For me, this is better than the accepted answer, because it keeps the decimal. – Morey

You might want to add "-" as well because the number can be negative as well. – Makebelieve

...but only if - is the first character – Rhizomorphous

this does WRONG for the input my text: 9123.11, okay.? – Solvent

Answer 7

The problem with these answers above, is that it assumes whole numbers. But if you need a floating point value, then the previous reg string will remove the decimal point.

To correct this you need write a negated character class with ^

var mystring = mystring.replace(/[^0-9.]/g, '');

Lynnett

this does WRONG for the input my text: 9123.11 okay. – Solvent

Answer 8

In Angular / Ionic / VueJS -- I just came up with a simple method of:

stripNaN(txt: any) {
    return txt.toString().replace(/[^a-zA-Z0-9]/g, "");
}

Usage on the view:

<a [href]="'tel:'+stripNaN(single.meta['phone'])" [innerHTML]="stripNaN(single.meta['phone'])"></a>

Sabir

Answer 9

Unfortunately none of the answers above worked for me.

I was looking to convert currency numbers from strings like $123,232,122.11 (1232332122.11) or USD 123,122.892 (123122.892) or any currency like ₹ 98,79,112.50 (9879112.5) to give me a number output including the decimal pointer.

Had to make my own regex which looks something like this:

str = str.match(/\d|\./g).join('');

Bluebeard

Answer 10

try

myString.match(/\d/g).join``

var myString = 'abc123.8<blah>'
console.log( myString.match(/\d/g).join`` );

Gluey

how does this work? – Platelet

@Platelet match will filter all digits and put them into array, join will glue array elements into single string – Megagamete

i meant the join with the backticks. what's going on there? – Platelet

@Platelet read about: js tagged templates – Megagamete

Yeah I've seen tagged templates, just don't understand what is going on with join using them. Is this just saving two characters, invoking join with a single argument ""? – Platelet

Answer 11

This,

.match(/\d|\.|\-/g).join('');

Handles both , and . also -

Example:

"Balance -$100,00.50".match(/\d|\.|\-/g).join('');

Outputs

-10000.50

Kisner

Answer 12

we are in 2017 now you can also use ES2016

var a = 'abc123.8<blah>';
console.log([...a].filter( e => isFinite(e)).join(''));

or

console.log([...'abc123.8<blah>'].filter( e => isFinite(e)).join(''));  

The result is

1238

Planetstruck

This is a very inefficient way to go about this operation. – Cann

It converts the string into an array of single-character strings via a spare method, and then applies filter function over JavaScript on each array item, returning a new string array, to finally join that array back into a string. Regex takes a string and returns a string and the processing is done via native code. – Stinkpot