JavaScript: Array.prototype.concat
arrayX.concat(new1, new2 etc)
- Return a new array by joining arguments to the array. Each argument can be any type. If it is a array, it will be flattened 1 level (That is, remove the outmost brackets).
// example of using array.concat() const mya = [1]; console.log( mya.concat( 2, [3], {k9:9}) ); // [ 1, 2, 3, { k9: 9 } ] console.log( mya ); // [1]
To add without flatten, use push. See: Array.prototype.push .
For how to flatten nested array, see: Array.prototype.flat .