locutus/php/strings/substr.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.substr = substr;
const _phpCastString_ts_1 = require("../_helpers/_phpCastString.js");
const ini_get_ts_1 = require("../info/ini_get.js");
function substr(input, start, len) {
    //  discuss at: https://locutus.io/php/substr/
    // original by: Martijn Wieringa
    // bugfixed by: T.Wild
    // improved by: Onno Marsman (https://twitter.com/onnomarsman)
    // improved by: Brett Zamir (https://brett-zamir.me)
    //  revised by: Theriault (https://github.com/Theriault)
    //  revised by: Rafał Kukawski
    //      note 1: Handles rare Unicode characters if 'unicode.semantics' ini (PHP6) is set to 'on'
    //   example 1: substr('abcdef', 0, -1)
    //   returns 1: 'abcde'
    //   example 2: substr(2, 0, -6)
    //   returns 2: false
    //   example 3: ini_set('unicode.semantics', 'on')
    //   example 3: substr('a\uD801\uDC00', 0, -1)
    //   returns 3: 'a'
    //   example 4: ini_set('unicode.semantics', 'on')
    //   example 4: substr('a\uD801\uDC00', 0, 2)
    //   returns 4: 'a\uD801\uDC00'
    //   example 5: ini_set('unicode.semantics', 'on')
    //   example 5: substr('a\uD801\uDC00', -1, 1)
    //   returns 5: '\uD801\uDC00'
    //   example 6: ini_set('unicode.semantics', 'on')
    //   example 6: substr('a\uD801\uDC00z\uD801\uDC00', -3, 2)
    //   returns 6: '\uD801\uDC00z'
    //   example 7: ini_set('unicode.semantics', 'on')
    //   example 7: substr('a\uD801\uDC00z\uD801\uDC00', -3, -1)
    //   returns 7: '\uD801\uDC00z'
    const str = (0, _phpCastString_ts_1._phpCastString)(input);
    const multibyte = (0, ini_get_ts_1.ini_get)('unicode.semantics') === 'on';
    const chars = multibyte ? str.match(/[\uD800-\uDBFF][\uDC00-\uDFFF]|[\s\S]/g) || [] : null;
    const inputLength = chars ? chars.length : str.length;
    let end = inputLength;
    if (start < 0) {
        start += end;
    }
    if (typeof len !== 'undefined') {
        if (len < 0) {
            end = len + end;
        }
        else {
            end = len + start;
        }
    }
    if (start > inputLength || start < 0 || start > end) {
        return false;
    }
    if (chars) {
        return chars.slice(start, end).join('');
    }
    return str.slice(start, end);
}