Does Javascript slice method return a shallow copy?

Question

In a Mozilla developer translated Korean lang says 'slice method' returns a new array copied shallowly.

so I tested my code.

var animals = ['ant', 'bison', 'camel', 'duck', 'elephant'];

var t = animals.slice(2,4);
console.log(t);

t[0] = 'aaa';
console.log(t);
console.log(animals);

but, If slice method returns shallow array, the animals array should be changed with ['ant', 'bison', 'aaa', 'duck', 'elephant'].

Why is it shallow copy?

Answer 1

strings are primitive types in JavaScript, so you will get a new array with new strings inside.

Your test array should be an array of objects:

var animals = [{name: 'ant'}, {name: 'bison'}, {name: 'camel'}, {name: 'duck'}, {name: 'elephant'}];

var t = animals.slice(2,4);
console.log(t);

t[0].name = 'aaa';
console.log(t);
console.log(animals);