how to use ! operator javascript code example

Example 1: javascript ... operator

//The operator ... is part of the array destructuring.
//It's used to extract info from arrays to single variables.
//The operator ... means "the rest of the array".
var [head, ...tail] = ["Hello", "I" , "am", "Sarah"];
console.log(head);//"Hello"
console.log(tail);//["I", "am", "Sarah"]

//It can be used to pass an array as a list of function arguments
let a = [2,3,4];
Math.max(a) //--> NaN
Math.max(...a) //--> 4

Example 2: javascript ... operator

let obj1 = { foo: 'bar', x: 42 };
let obj2 = { foo: 'baz', y: 13 };

let clonedObj = { ...obj1 };
// Object { foo: "bar", x: 42 }

let mergedObj = { ...obj1, ...obj2 };
// Object { foo: "baz", x: 42, y: 13 }