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JavaScript: Decapitalize the first letter of a string

JavaScript fundamental (ES6 Syntax): Exercise-24 with Solution

Write a JavaScript program to decapitalize the first letter of a string.

  • Use array destructuring and String.prototype.toLowerCase() to decapitalize first letter, ...rest to get array of characters after first letter and then Array.prototype.join('') to make it a string again.
  • Omit the upperRest argument to keep the rest of the string intact, or set it to true to convert to uppercase.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const decapitalize = ([first, ...rest], upperRest = false) =>
  first.toLowerCase() + (upperRest ? rest.join('').toUpperCase() : rest.join(''));
console.log(decapitalize('W3resource'))
console.log(decapitalize('Red', true));

Note: Omit the upperRest parameter to keep the rest of the string intact, or set it to true to convert to uppercase

Sample Output:

w3resource
rED

Pictorial Presentation:

JavaScript Fundamental: Decapitalize the first letter of a string

Flowchart:

flowchart: Decapitalize the first letter of a string

Live Demo:

See the Pen javascript-basic-exercise-1-24 by w3resource (@w3resource) on CodePen.


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Previous: Write a JavaScript program to filter out the non-unique values in an array, based on a provided comparator function.
Next: Write a JavaScript program to create a new array out of the two supplied by creating each possible pair from the arrays.

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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