How to Extract Numbers From a String in JavaScript

While working on certain tasks with JavaScript, such as web scraping, we might need to extract specific data from a string, such as uppercase words or numbers. In this post, I am going to address numbers.

The numbers may also be:

decimal - examples: average, price, score.
negative - examples: temperature, mathematical calculations.
comma-separated - example: large amounts such as appear in telephone numbers or bank statements.

Or a combination of any of these.

For example, a simple short text such as:

The World Population at the start of 2023 is 8,009,975,957. It crossed 8 billion mark in 2022.

should return:

[
  "2023",
  "8,009,975,957",
  "8",
  "2022"
]

or in number form (without string/commas):

[
  2023,
  8009975957,
  8,
  2022
]

To see it working interactively, provide a text to this Extract Numbers utility app, and get a list of extracted numbers.

To get all the possible numbers out of the string requires a regex. And I’ve found one that addresses most of the above cases, plus their combinations.

In case you are looking for a JavaScript library, it’s available as extract-numbers on NPM. It has no dependency.

The Regex And The Code

Regex

  /(-\d+|\d+)(,\d+)*(\.\d+)*/g

Code

const extractNumbers = (text, options) => {
  let numbers;
  if (!text || typeof text !== 'string') {
    return [];
  }

  numbers = text.match(/(-\d+|\d+)(,\d+)*(\.\d+)*/g);

  return numbers;
};

Code to Optionally Convert the Resultant Strings to Numbers

Change the method call to extractNumbers(str, {string: false});, and replace the function code with:

const extractNumbers = (text, options) => {
  let numbers;
  options = options || {};
  if (!text || typeof text !== 'string') {
  return [];
  }

  numbers = text.match(/(-\d+|\d+)(,\d+)*(\.\d+)*/g);

  if (options.string === false) {
  numbers = numbers.map(n => Number(n.replace(/,/g, '')));
  }

  return numbers;
};

javascript npm

How to Extract Numbers From a String in JavaScript

Including decimals, negatives, and numbers with commas.

The Regex And The Code

Regex

Code

Code to Optionally Convert the Resultant Strings to Numbers

See also