How to clone array of objects TypeScript?

Question

I tried this approach:

this.plans = [];
this.plansCopy = [...this.plans];

Seems it does not work cause returns duplictions.

Answer 1

The spread operator returns the individual items of the array. If these are already objects, then it's returning the references to those objects. It's the [] part that is creating a new array. Thus you have a new array, but it will still contain the same object references, so this.plans[0].oper() will call this.plansCopy[0].oper() at the same time as well.

Instead you need to clone each individual object. There are a lot of different ways to do this (create deep copy of the array or individual objects). If you only need one level of cloning you can do:

this.plansCopy = this.plans.map(obj => ({...obj}));

This will create a new array where each element is a copy of each object.