using the spread operator in react state code example

Example 1: react spread operator

let numberStore = [0, 1, 2];
let newNumber = 12;
numberStore = [...numberStore, newNumber];

Example 2: spread operator react

{...this.state} spreads out the "own" enumerable properties in 
props as discrete properties on the Modal element you're creating. 
For instance, if this.props contained a: 1 and b: 2, then

<Modal {...this.state} title='Modal heading'>

would be the same as

<Modal a={this.state.a} b={this.state.b} title='Modal heading'>