js · 2024-12-30

Array.prototype.flatMap

The flatMap method is a combination of calling map followed by flat. It simplifies the process of mapping over an array and flattening the result in one step.

Example:

This method is particularly useful for extracting arrays from an array of objects and flattening the structure.

const users = [
    {
        id: 1,
        roles: [1, 5, 8],
    },
    {
        id: 2,
        roles: [2, 3],
    },
];

const roles = users.flatMap((user) => user.roles);
console.log(roles);
// Output: [1, 5, 8, 2, 3]

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