If you are a TypeScript developer, add any of these snippets to Pieces for some extreme time-saving shortcuts. Coding in TypeScript can be challenging and getting used to the intricacies of adding typing to traditional JavaScript can be quite confusing.
This collection of TypeScript examples is aimed at helping you perform common TypeScript and JavaScript operations. No matter your experience level, from beginner to advanced, the following TypeScript code samples will be useful for all developers.
How to pick properties from interface in TypeScript
Tags: typescript, pick
Construct a new type based on partial properties of an interface.
interface MyInterface {
id: number;
name: string;
properties: string[];
}
type MyShortType = Pick;
Related links:
- TypeScript utility types
- How to use pick in TypeScript
How to use TypeScript to exclude a property from an interface
Tags: typescript, omit
Exclude properties from a given interface with this TypeScript snippet.
interface MyInterface {
id: number;
name: string;
properties: string[];
}
type MyShortType = Omit;
Related links:
- TypeScript utility types
- Omit type in TypeScript
How to use TypeScript to get a value of an interface property
Tags: typescript, get value
Get value of an object with an interface using this TypeScript code sample.
interface MyInterface {
id: number;
name: string;
properties: string[];
}
const myObject: MyInterface = {
id: 1,
name: 'foo',
properties: ['a', 'b', 'c']
};
function getValue(value: keyof MyInterface) {
return myObject[value];
}
getValue('id'); // 1
getValue('count')
Related links:
- Keyof TypeScript snippets
How to store a record as a string with interface in TypeScript
Tags: typescript, record
Map a string key to a custom interface in an object.
const myTypedObject: Record = {
first: {...},
second: {...},
...
};
Related links:
- TypeScript utility types
- Record typed in TypeScript
- TypeScript record type explained
How to check if a collection of elements are true in TypeScript
Tags: typescript, every, collection
Returns true if all elements in a collection are true.
const all = (arr: T[], fn: (t: T) => boolean = Boolean) => arr.every(fn);
Related links:
- Array prototype every - TypeScript code snippets
- TypeScript Array Every
How to check if at least one element passes in a function using TypeScript
Tags: typescript, some
Tests whether at least one element in the array passes the test implemented by a provided function.
const some = (arr: T[], fn: (t: T) => boolean = Boolean) => arr.some(fn);
Related links:
- Array Prototype Some - TypeScript example
- TypeScript Array Some Examples
How to remove falsy values from an array using TypeScript
Tags: typescript, filter, compact
Removes falsy values from an array. See our JavaScript snippets collection for the JS version of this TypeScript code snippet.
const compact = (arr: any[]) => arr.filter(Boolean);
Related links:
- Remove all falsy values from an array
How to delay async executions using TypeScript
Tags: typescript, async, setTimeout
Turns setTimeout into a promise that can be used asynchronously.
const timeoutPromise: (duration: number) => Promise = (duration: number): Promise => new Promise(resolver => setTimeout(resolver, duration));
Related links:
- Combination of functions - Async + wait + setTimeout
- Using a setTimeout in an async function - Typescript Snippets
- How to make TypeScript setTimeout async friendly
TypeScript function composition
Tags: typescript, composition
Performs left to right function composition.
const compose = (...fns: Func[]) => {
fns.reduce((f, g) => (...args: any[]) => f(...castArray(g(...args))));
}
Related links:
- Function composition in Javascript - Explained
- How to do function composition in JavaScript
TypeScript debounce example
Tags: typescript, debounce
Delays invoking a provided function at least since specified milliseconds have elapsed.
const debounce = (fn: Function, ms = 300) => {
let timeoutId: ReturnType;
return function (this: any, ...args: any[]) {
clearTimeout(timeoutId);
timeoutId = setTimeout(() => fn.apply(this, args), ms);
};
};
Related links:
- How to delay a function in JavaScript - Debounce example
- TypeScript Debounce function - troubleshooting
How to create a deep clone in TypeScript
Tags: typescript, clone, deep clone
These TypeScript code snippets create a deep clone of an object.
const deepClone = (obj: any) => {
if (obj === null) return null;
let clone = { ...obj };
Object.keys(clone).forEach(
(key) =>
(clone[key] = typeof obj[key] === "object" ? deepClone(obj[key]) : obj[key])
);
return Array.isArray(obj) && obj.length
? (clone.length = obj.length) && Array.from(clone)
: Array.isArray(obj)
? Array.from(obj)
: clone;
};
Related links:
- Deep Clone an Object and Preserve its Type - TypeScript code sample
- Deep clone TypeScript - Troubleshooting
How to find the key that meets a condition in TypeScript
Tags: typescript, find key
Returns the first key that meets a condition specified from the passed function.
const findKey = (obj: any, fn: Function) => Object.keys(obj).find((key) => fn(obj[key], key, obj));
Related links:
- How to get an Object's Key by Value in TypeScript
- How to find key and value in object JavaScript
Find intersection of two arrays using TypeScript
Tags: typescript, intersection
Returns a list of elements that exist in both arrays.
const intersection = (a: any[], b: any[]) => {",
const s = new Set(b);
return [...new Set(a)].filter((x) => s.has(x));
};
Related links:
- Set JavaScript example
- Map Prototype Has - JavaScript examples
How to check if an array is empty in TypeScript
Tags: typescript, is empty
Checks if a value is an empty object, array, or null.
const isEmpty = (val: any) => val == null || !(Object.keys(val) || val.length;
Related links:
- TypeScript check if object is empty
- Why do empty JavaScript arrays evaluate to true in conditional structures?
How to use Async in TypeScript
Tags: typescript, async
Create a promise using Typescript with a void return value.
const fetchData = async (): Promise => {
// ...
};
Related links:
- How to use async await in TypeScript
- How to create a promise function in JavaScript
How to convert object to array in TypeScript
Tags: typescript, array to object
Turns an Array into an Object.
const arrayToObj = (array: T[]): { [k: string]: T } => {
const out: { [k: string]: T } = {};
array.forEach((val) => {
out[val.id] = val;
});
return out;
};
Related links:
- How to Convert a JavaScript Array to Dictionary / Hashmap
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