JavaScript string repeat methods All In One

JavaScript string repeat methods All In One

There are many ways in the ES-Next ways

repeat

ES2015 / ES6

/**
 * str: String
 * count: Number
 */
const str = `hello repeat!\n`, count = 3;

let resultString = str.repeat(count);

console.log(`resultString = \n${resultString}`);
/*
resultString =
hello repeat!
hello repeat!
hello repeat!
*/

({ toString: () => 'abc', repeat: String.prototype.repeat }).repeat(2);
// 'abcabc' (repeat() is a generic method)

// Examples

'abc'.repeat(0);    // ''
'abc'.repeat(1);    // 'abc'
'abc'.repeat(2);    // 'abcabc'
'abc'.repeat(3.5);  // 'abcabcabc' (count will be converted to integer)
// 'abc'.repeat(1/0);  // RangeError
// 'abc'.repeat(-1);   // RangeError

padStart

ES2017 / ES8

const str = 'abc ';
const times = 3;

const newStr = str.padStart(str.length * times, str.toUpperCase());

console.log(`newStr =`, newStr);
// "newStr =" "ABC ABC abc "

padEnd

ES2017 / ES8

const str = 'abc ';
const times = 3;

const newStr = str.padEnd(str.length * times, str.toUpperCase());

console.log(`newStr =`, newStr);
// "newStr =" "abc ABC ABC "

refs

https://stackoverflow.com/a/41574167/5934465

https://www.ecma-international.org/ecma-262/6.0/#sec-string.prototype.repeat

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/repeat

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padStart

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padEnd

https://www.freecodecamp.org/news/three-ways-to-repeat-a-string-in-javascript-2a9053b93a2d/

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