mirror of
https://github.com/whoisclebs/lodash.git
synced 2026-01-31 15:27:50 +00:00
47 lines
1.1 KiB
JavaScript
47 lines
1.1 KiB
JavaScript
/* Used as references for the maximum safe integer in JavaScript Math.pow(2, 53) - 1 */
|
|
const MAX_SAFE_INTEGER = 9007199254740991
|
|
|
|
/* Built-in method references for those with the same name as other `lodash` methods. */
|
|
const nativeFloor = Math.floor
|
|
|
|
/**
|
|
* Repeats the given string `n` times.
|
|
*
|
|
* @since 3.0.0
|
|
* @category String
|
|
* @param {string} [string=''] The string to repeat.
|
|
* @param {number} [n=1] The number of times to repeat the string.
|
|
* @returns {string} Returns the repeated string.
|
|
* @example
|
|
*
|
|
* repeat('*', 3)
|
|
* // => '***'
|
|
*
|
|
* repeat('abc', 2)
|
|
* // => 'abcabc'
|
|
*
|
|
* repeat('abc', 0)
|
|
* // => ''
|
|
*/
|
|
function repeat(string, n) {
|
|
let result = ''
|
|
if (!string || n < 1 || n > MAX_SAFE_INTEGER) {
|
|
return result
|
|
}
|
|
// Leverage the exponentiation by squaring algorithm for a faster repeat.
|
|
// See https://en.wikipedia.org/wiki/Exponentiation_by_squaring for more details.
|
|
do {
|
|
if (n % 2) {
|
|
result += string
|
|
}
|
|
n = nativeFloor(n / 2)
|
|
if (n) {
|
|
string += string
|
|
}
|
|
} while (n)
|
|
|
|
return result
|
|
}
|
|
|
|
export default repeat
|