To convert a multidimensional or nested array into a single array or flatten the array we can use the flat() method available in the array.
Suppose you have a nested array like this,
// nested array
let arr = ["John Doe", ["Lily Rose", 23]];
Let's convert this array into a single array using the flat() method available in the array.
// nested array
let arr = ["John Doe", ["Lily Rose", 23]];
// convert nested array into single array
let convertedArr = arr.flat();
console.log(convertedArr); // ["John Doe", "Lily Rose", 23]
By default, arr.flat() method only converts nested arrays up to 1 level deep.
What if we have nested arrays which are 3 levels deep like this,
// nested array with 3 levels
let arr = ["John Doe", ["Lily Rose", ["salary", ["baseSalary", 23000]]]];
For this to convert into a single array we can pass the depth to which we want to convert the array as an argument to the flat() method.
// nested array with 3 levels
let arr = ["John Doe", ["Lily Rose", ["salary", ["baseSalary", 23000]]]];
// converted nested array into single array which is 3 levels deep
let convertedArr = arr.flat(3);
console.log(convertedArr); // ["John Doe", "Lily Rose", "salary", "baseSalary", 23000]