w3resource

JavaScript: Convert a string to snake case

JavaScript fundamental (ES6 Syntax): Exercise-120 with Solution

Write a JavaScript program to convert a string to snake case.

Note: Break the string into words and combine them adding _ as a separator, using a regexp.

  • Use String.prototype.match() to break the string into words using an appropriate regexp.
  • Use Array.prototype.map(), Array.prototype.slice(), Array.prototype.join() and String.prototype.toLowerCase() to combine them, adding _ as a separator.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2
const toSnakeCase = str =>
  str &&
  str
    .match(/[A-Z]{2,}(?=[A-Z][a-z]+[0-9]*|\b)|[A-Z]?[a-z]+[0-9]*|[A-Z]|[0-9]+/g)
    .map(x => x.toLowerCase())
    .join('_');

console.log(toSnakeCase('camelCase'));
console.log(toSnakeCase('some text'));
console.log(toSnakeCase('some-mixed_string With spaces_underscores-and-hyphens'));
console.log(toSnakeCase('AllThe-small Things'));
console.log(toSnakeCase('IAmListeningToFMWhileLoadingDifferentURLOnMyBrowserAndAlsoEditingSomeXMLAndHTML'));

Sample Output:

camel_case
some_text
some_mixed_string_with_spaces_underscores_and_hyphens
all_the_small_things
i_am_listening_to_fm_while_loading_different_url_on_my_browser_and_also_editing_some_xml_and_html

Pictorial Presentation:

JavaScript Fundamental: Convert a string to snake case.

Flowchart:

flowchart: Convert a string to snake case

Live Demo:

See the Pen javascript-basic-exercise-120-1 by w3resource (@w3resource) on CodePen.


Improve this sample solution and post your code through Disqus

Previous: Write a JavaScript program to create tomorrow's date in a string representation.
Next: Write a JavaScript program to convert a value to a safe integer.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



JavaScript: Tips of the Day

How to remove a specific item from an array?

Find the index of the array element you want to remove using indexOf, and then remove that index with splice.

The splice() method changes the contents of an array by removing existing elements and/or adding new elements.

const array = [2, 5, 9];

console.log(array);

const index = array.indexOf(5);
if (index > -1) {
  array.splice(index, 1);
}

// array = [2, 9]
console.log(array);

The second parameter of splice is the number of elements to remove. Note that splice modifies the array in place and returns a new array containing the elements that have been removed.

For the reason of completeness, here are functions. The first function removes only a single occurrence (i.e. removing the first match of 5 from [2,5,9,1,5,8,5]), while the second function removes all occurrences:

function removeItemOnce(arr, value) {
  var index = arr.indexOf(value);
  if (index > -1) {
    arr.splice(index, 1);
  }
  return arr;
}

function removeItemAll(arr, value) {
  var i = 0;
  while (i < arr.length) {
    if (arr[i] === value) {
      arr.splice(i, 1);
    } else {
      ++i;
    }
  }
  return arr;
}
//Usage
console.log(removeItemOnce([2,5,9,1,5,8,5], 5))
console.log(removeItemAll([2,5,9,1,5,8,5], 5))

Ref: https://bit.ly/2N9nKRp