javascript - Reactjs: Is it necessary to copy object in component state before modifying it? -

suppose my reactjs component has 2 states:

a: {     a: 1 }, b: [1, 2, 3]

now want them become:

a: {     a: 1,     b: true }, b: [1, 2, 3, 4]

is correct by:

this.state.a.b = true; b = this.state.b.push(4); this.setstate({     a: this.state.a,     b: b });

if not, appropriate way it.

best way it.

  this.setstate({     a: object.assign({}, this.state.a, { b: true }),     b: [...this.state.b, 4]   });

EEE