How to find a number in a string using JavaScript?

Question

Suppose I have a string like - "you can enter maximum 500 choices". I need to extract 500 from the string.

The main problem is the String may vary like "you can enter maximum 12500 choices". So how to get the integer part?

Answer 1

I like @jesterjunk answer, however, a number is not always just digits. Consider those valid numbers: "123.5, 123,567.789, 12233234+E12"

So I just updated the regular expression:

var regex = /[\d|,|.|e|E|\+]+/g;

var string = "you can enter maximum 5,123.6 choices";
var matches = string.match(regex);  // creates array from matches

document.write(matches); //5,123.6

Answer 2

var regex = /\d+/g;
var string = "you can enter 30%-20% maximum 500 choices";
var matches = string.match(regex);  // creates array from matches

document.write(matches);

Answer 3

You can also try this :

var string = "border-radius:10px 20px 30px 40px";
var numbers = string.match(/\d+/g).map(Number);
console.log(numbers)

Answer 4

// stringValue can be anything in which present any number
`const stringValue = 'last_15_days';
// /\d+/g is regex which is used for matching number in string
// match helps to find result according to regex from string and return match value
 const result = stringValue.match(/\d+/g);
 console.log(result);`

output will be 15

If You want to learn more about regex here are some links:

https://www.w3schools.com/jsref/jsref_obj_regexp.asp

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

https://www.tutorialspoint.com/javascript/javascript_regexp_object.htm

Answer 5

var str = "you can enter maximum 500 choices";
str.replace(/[^0-9]/g, "");
console.log(str); // "500"

Answer 6

Use a regular expression.

var r = /\d+/;
var s = "you can enter maximum 500 choices";
alert (s.match(r));

The expression \d+ means "one or more digits". Regular expressions by default are greedy meaning they'll grab as much as they can. Also, this:

var r = /\d+/;

is equivalent to:

var r = new RegExp("\d+");

See the details for the RegExp object.

The above will grab the first group of digits. You can loop through and find all matches too:

var r = /\d+/g;
var s = "you can enter 333 maximum 500 choices";
var m;
while ((m = r.exec(s)) != null) {
  alert(m[0]);
}

The g (global) flag is key for this loop to work.