JavaScript: Capitalize the first letter of a string
JavaScript fundamental (ES6 Syntax): Exercise-263 with Solution
Write a JavaScript program to capitalize the first letter of a string.
- Use array destructuring and String.prototype.toUpperCase() to capitalize the first letter of the string.
- Use Array.prototype.join('') to combine the capitalized first with the ...rest of the characters.
- Omit the lowerRest argument to keep the rest of the string intact, or set it to true to convert to lowercase.
Sample Solution:
JavaScript Code:
//#Source https://bit.ly/2neWfJ2
const capitalize = ([first, ...rest], lowerRest = false) =>
first.toUpperCase() + (lowerRest ? rest.join('').toLowerCase() : rest.join(''));
console.log(capitalize('fooBar'));
console.log(capitalize('fooBar', true));
Sample Output:
FooBar Foobar
Pictorial Presentation:
Flowchart:

Live Demo:
See the Pen javascript-basic-exercise-263-1 by w3resource (@w3resource) on CodePen.
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Previous: Write a JavaScript program to create a base-64 encoded ASCII string from a String object in which each character in the string is treated as a byte of binary data.
Next: Write a JavaScript program to capitalize the first letter of every word in a string.
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JavaScript: Tips of the Day
How to check whether a string contains a substring in JavaScript?
ECMAScript 6 introduced String.prototype.includes:
const string = "foo"; const substring = "oo"; console.log(string.includes(substring));
includes doesn't have Internet Explorer support, though. In ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 when a substring cannot be found:
var string = "foo"; var substring = "oo"; console.log(string.indexOf(substring) !== -1);
Ref: https://bit.ly/3fFFgZv
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