Why does this object update affect both variables?

programming web dev
1

Small JavaScript fundamentals check.

const a = { theme: 'dark' };
const b = a;
b.theme = 'light';
console.log(a.theme);

Why does this happen, and what is a simple way to avoid it.

Yoshiii :slightly_smiling_face:

2

Because b = a copies the reference, not the object, so both names point at the same thing; if you want a separate object, clone it first.

const a = { theme: 'dark' };
const b = { ...a };
b.theme = 'light';

Tiny caveat: spread only does a shallow copy, so nested objects still share references.

WaffleFries