Imagine the String() constructor didn't exist. Create a constructor function

Imagine the String() constructor didn't exist. Create a constructor function
0

#1

I came across the following exercise in an OOP book form Packt, and was wondering how other people might approach the solution. I’ve started on mine but feel I might be barking up the wrong tree and not fully understanding the exercise:

Exercise

Imagine the String() constructor didn’t exist. Create a constructor function, MyString(), that acts like String() as closely as possible. You’re not allowed to use any built-in string methods or properties, and remember that String() doesn’t exist. You can use this code to test your constructor:


> var s = new MyString('hello');
> s.length;
      5
> s[0];
      "h"
> s.toString();
      "hello"
> s.valueOf();
      "hello"
> s.charAt(1);
      "e"
> s.charAt('2');
      "l"
> s.charAt('e');
      "h"
> s.concat(' world!');
      "hello world!"
> s.slice(1, 3);
      "el"
> s.slice(0, -1);
      "hell"
> s.split('e');
      ["h", "llo"]
> s.split('l');
      ["he", "", "o"]

Note: You can use a for loop to loop through the input string, treating it as an array.

My current incomplete solution

function MyString(str){
 var arr = Array.from(str);
 this.length = arr.length;
 this.toString = function() {
   return arr.join('');
 };
 this.valueOf = function() {
   return arr.join('');
 };
 this.charAt = function(value) {
   value = (!parseInt(value)) ? 0 : parseInt(value);
   return arr[value];
 };
 this.concat = function(value) {
   return arr.join('') + value;
 };
 this.slice = function(start, end) {
   var slice = '';
   for (var j = start; j < end; j ++){
     slice += arr[j];
   }
   return slice;
 };
 this.split = function(seperator) {
   var split = [];
   for (var letter in str){
     if (seperator !== str[letter]){
       split.push(str[letter]);
     }
   }
   return split;
 };
}