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Helpers

The @perseid/core package offers a collection of isomorphic helper functions that are useful for a wide range of projects.

forEach​

Implementation of JS Array.forEach method, adapted to asynchronous callbacks.

function forEach<T>(
  items: T[],
  callback: (item: T, index: number) => Promise<void>,
): Promise<void>;

Parameters​

  • items: Items to iterate on.
  • callback: Asynchronous function to execute for each item.

Returns​

Translated label.

Usage​

[1, 2, 3].forEach(async (item) => {
  await doSomethingAsync(item);
});

toSnakeCase​

Transforms text into SNAKE_CASE.

function toSnakeCase(text: string): string;

Parameters​

  • text: Text to transform.

Returns​

Transformed text.

Usage​

toSnakeCase('helloWorld'); // HELLO_WORLD

isPlainObject​

Returns true if variable is a plain object, false otherwise.

function isPlainObject<T>(variable: T): boolean;

Parameters​

  • variable: Variable to check.

Returns​

true if variable is a plain object, false otherwise.

Usage​

isPlainObject(189); // false
isPlainObject(null); // false
isPlainObject([1, 2, 3]); // false
isPlainObject(new Date()); // false
isPlainObject({ hello: 'world' }); // true

deepCopy​

Performs a deep copy of variable. Only plain objects and arrays are deeply copied.

function deepCopy<T>(variable: T): T;

Parameters​

  • variable: Variable to deeply copy.

Returns​

Variable deep copy.

Usage​

const object = { hello: 'world', subObject: { key: 'test' } };
const objectDeepCopy = deepCopy(object);
object === objectDeepCopy; // false
object.subObject === objectDeepCopy.subObject; // false
JSON.stringify(object) === JSON.stringify(objectDeepCopy); // true

deepMerge​

Performs a deep merge of firstVariable and secondVariable. Only plain objects and arrays are deeply merged. In any other case, secondVariable is returned if it is defined.

function deepMerge<T1, T2>(
  firstVariable: T1,
  secondVariable: T2,
): T1 & T2;

Parameters​

  • firstVariable: First object.
  • secondVariable: Second object.

Returns​

Variables deep merge.

Usage​

// { hello: 'world', subObject: { key: 'test', key2: 'test2' } }
deepMerge({ hello: 'world', subObject: { key: 'test' } }, { subObject: { key2: 'test2' } });