example.md

most, but not all (notably sort and reverse on arrays) methods on arrays and strings will not modify the string or array

for example

var myString = 'qwerty';
console.log(myString.split('')); // ['q','w','e','r','t','y']
console.log(myString); // 'qwerty'

myString.toUpperCase();
console.log(myString); // still 'qwerty'

to use the results of a manipulation we must store it in a variable

var myArray = myString.split('');
console.log(myString); // still 'qwerty'
console.log(myArray); // ['q','w','e','r','t','y']