String (JavaScript)

A primitive that represents a list of characters. Strings are immutable, indexable, and iterable.

Creating Strings

String literals

const str = 'Hello world';
str;

'Hello world'

String templates

const str = `answer: ${40 + 2}`;
str;

'answer: 42'

From other types

const str = String(4);
str;

'4'

'abc'[0];

'a'

'abc'.at(-1);

'c'

'abc'.length;

<, <=, ===, >, and >= operators can be used.

'apple' < 'banana'

true

'apple' === 'apple'

true

.localeCompare(str) is a comparator

'apple'.localeCompare('banana');

-1

'apple'.localeCompare('apple');

'Hello' + 'World';

'HelloWorld'

['Hello', 'World'].join(' ');

'Hello World'

includes

'abcdef'.includes('cd');

true

indexOf

const str = 'abcdef';
str.indexOf('cd');

str.indexOf('z');

-1

split

'split on space'.split(' ');

['split', 'on', 'space']

slice

const str = 'abcdefg';
str.slice(0, 2);

'ab'

str.slice(1, 4);

'bcd'

Manage Casing

const str = 'Hello World';
str.toUpperCase();

'HELLO WORLD';

str.toLowerCase();

'hello world'

Replacing

'ab??d'.replace('?', 'c');

'abc?d'

'ab??d'.replaceAll('?', 'c');

'abccd'

Whitespace Trimming

'  whitespace   '.trim();

'whitespace'

const str = 'abc';
for (let i = 0; i < str.length; i++) {
  console.log(str[i]);
}

a
b
c

for (const char of 'abc') {
  console.log(char);
}

a
b
c