removePrefix.js

// zambian mobile numbers start with 09x in case the user typed it start with a 2 
// then its a country code prefixed

    // es6 
    const removePrefix = num => num[0] == 2 ? num.substring(3) : num[0] == 0 ? num.substring(1) : num;

  // es5   
  function removePrefix(num){
      if(num[0] == 2){ // check if it starts with a 2
        return num.substring(3) // remove numbers up to index 2 of the value
      } else if(num[0] == 0){ // check if the value starts with a zero
          return num.substring(1) // remove the o
      }
      return num 
  }