Create a function that emulates the '../' function in the command line

changeDirectory.js

let str1 = '/a/b/../foo/.///';
let str2 = '/a/./b/../../c';
let str3 = '/home';
let str4 = '/a/../../../b';
let str5 = '/../';

function changeDirectory(str) {
    let result = "",
        ignoreChars = ['.', '..', '/', '//', ''],
        directoryArr = str.split('/');
        
    for (let ele of directoryArr) {
        if (ele === '..') {
            result = result.slice(0, result.length -2);
        }
        if (!ignoreChars.includes(ele)) {
            result += ele + '/';
        }
    }
    return '/' + result.slice(0, result.length - 1); //without the trailing slash :)
}

changeDirectory(str1); //returns /a/foo
changeDirectory(str2); //returns /c
changeDirectory(str3); //returns /home
changeDirectory(str4); //returns /b
changeDirectory(str5); //returns /

Change ignoreChars to a Set to make the runtime more efficient