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- 'use strict';
- var $TypeError = require('es-errors/type');
- var callBound = require('call-bind/callBound');
- var isInteger = require('../helpers/isInteger');
- var $strSlice = callBound('String.prototype.slice');
- // https://262.ecma-international.org/15.0/#sec-stringpad
- module.exports = function StringPad(S, maxLength, fillString, placement) {
- if (typeof S !== 'string') {
- throw new $TypeError('Assertion failed: `S` must be a String');
- }
- if (!isInteger(maxLength) || maxLength < 0) {
- throw new $TypeError('Assertion failed: `maxLength` must be a non-negative integer');
- }
- if (typeof fillString !== 'string') {
- throw new $TypeError('Assertion failed: `fillString` must be a String');
- }
- if (placement !== 'start' && placement !== 'end' && placement !== 'START' && placement !== 'END') {
- throw new $TypeError('Assertion failed: `placement` must be ~START~ or ~END~');
- }
- var stringLength = S.length; // step 1
- if (maxLength <= stringLength) { return S; } // step 2
- if (fillString === '') { return S; } // step 3
- var fillLen = maxLength - stringLength; // step 4
- // 5. Let _truncatedStringFiller_ be the String value consisting of repeated concatenations of _fillString_ truncated to length _fillLen_.
- var truncatedStringFiller = '';
- while (truncatedStringFiller.length < fillLen) {
- truncatedStringFiller += fillString;
- }
- truncatedStringFiller = $strSlice(truncatedStringFiller, 0, fillLen);
- if (placement === 'start' || placement === 'START') { return truncatedStringFiller + S; } // step 6
- return S + truncatedStringFiller; // step 7
- };
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