Andrew's Utils

A collection of random useful utility functions that you may not find in lodash. These utility functions are emitted as ES6 modules so that they are tree-shakable.

Type Guards

This utility library provides a series of generic TypeScript type guards for validating your data.

$3

This type guard validates that the provided object contains the provided property names.

#### hasOwnProperties Interface

``typescript
function hasOwnProperties<
X extends Record,
Y extends PropertyKey,
A extends Y[]
>(obj: X, props: A) => obj is X & Record;
`

$3

`typescript
import { isObject, hasOwnProperties } from 'andrews-utils';

const val: unknown = {
foo: 'bar',
hello: 'world',
};

if (isObject(val) && hasOwnProperties(val, ['foo', 'hello'])) {
// -> do something with obj.foo or obj.hello
}
`

---

$3

This type guard validates that the provided object contains the provided property.

#### hasOwnProperty Interface

`typescript
function hasOwnProperty, Y extends PropertyKey>(
obj: X,
prop: Y
) => obj is X & Record;
`

$3

`typescript
import { isObject, hasOwnProperty } from 'andrews-utils';

const val: unknown = {
foo: 'bar',
hello: 'world',
};

if (isObject(val) && hasOwnProperty(val, 'foo')) {
}
`

---

$3

This type guard validates that the provided value is an array.

#### isArray Interface

`typescript
function isArray(value: unknown) => value is unknown[];
`

$3

`typescript
import { isArray } from 'andrews-utils';

const arr: unknown = ['foo', 'bar'];

if (isArray(arr)) {
arr.forEach(val => {});
}
`

---

$3

This type guard validates that the provided value is a number.

#### isNumber Interface

`typescript
function isNumber(value: unknown) => value is number;
`

$3

`typescript
import { isNumber } from 'andrews-utils';

const val: unknown = 123;

if (isNumber(val)) {
const answer = val * 2;
}
`

---

$3

This type guard validates that the provided value is an object.

#### isObject Interface

`typescript
function isObject(value: unknown) => value is Record;
`

$3

`typescript
import { isObject } from 'andrews-utils';

const obj: unknown = {
foo: 'bar',
};

if (isObject(val)) {
// Do something with object with unknown properties.
// Usually you would combine this with the hasOwnProperties type guard.
}
`

---

$3

This type guard validates that the provided value is not undefined or null.

#### isSet Interface

`typescript
function isSet(value?: unknown) => value is NonNullable;
`

$3

`typescript
import { isSet } from 'andrews-utils';

const val: unknown = 123;

if (isSet(val)) {
const answer = val * 2;
}
`

---

$3

This type guard validates that the provided value is a string.

#### isString Interface

`typescript
function isString(value: unknown) => value is string;
`

$3

`typescript
import { isString } from 'andrews-utils';

const val: unknown = 'foo';

if (isString(val)) {
const chars = val.split('');
}
`

---

$3

Executes a standard fetch but returns the JSON response as unknown to force you to validate it.

#### safeJsonFetch Interface

`typescript
async function safeJsonFetch(
input: RequestInfo | URL,
init?: RequestInit | undefined
) => Promise;
`

$3

`typescript
import { safeJsonFetch } from 'andrews-utils';

safeJsonFetch('https://example.com/user/1').then(json => {
const answer = json * 2;
// => TSError: Object is of type 'unknown'.ts(2571)
// This error is expected because json should be of type unknown.
});
``