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Improve the TypeScript types

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Use more type guards.
This commit is contained in:
Sindre Sorhus 2019-02-02 03:02:47 +07:00
parent cbd9f061c5
commit f0c73b0f21
3 changed files with 56 additions and 42 deletions
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89
source/index.ts
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@ -8,7 +8,9 @@
const URLGlobal = typeof URL === 'undefined' ? require('url').URL : URL;
type TypedArray = Int8Array | Uint8Array | Uint8ClampedArray | Int16Array | Uint16Array | Int32Array | Uint32Array | Float32Array | Float64Array;
type Primitive = null | undefined | string | number | boolean | Symbol;
// TODO: This should be able to be `not object` when the `not` operator is out
type Primitive = null | undefined | string | number | boolean | symbol;
export interface ArrayLike {
length: number;
@ -16,8 +18,8 @@ export interface ArrayLike {
export type Class<T = unknown> = new(...args: any[]) => T;
type DomElement = object & { nodeType: 1; nodeName: string };
type NodeStream = object & { pipe: Function };
type DomElement = object & {nodeType: 1; nodeName: string};
type NodeStream = object & {pipe: Function};
export const enum TypeName {
null = 'null',
@ -58,11 +60,9 @@ export const enum TypeName {
const toString = Object.prototype.toString;
const isOfType = <T>(type: string) => (value: unknown): value is T => typeof value === type;
const isBuffer = (input: unknown): input is Buffer => !is.nullOrUndefined(input) && !is.nullOrUndefined((input as Buffer).constructor) && is.function_((input as Buffer).constructor.isBuffer) && (input as Buffer).constructor.isBuffer(input);
const getObjectType = (value: unknown): TypeName | null => {
const objectName = toString.call(value).slice(8, -1);
if (objectName) {
return objectName as TypeName;
}
@ -72,7 +72,8 @@ const getObjectType = (value: unknown): TypeName | null => {
const isObjectOfType = <T>(type: TypeName) => (value: unknown): value is T => getObjectType(value) === type;
function is(value: unknown): TypeName { // tslint:disable-line:only-arrow-functions
// tslint:disable-next-line: no-use-before-declare
function is(value: unknown): TypeName {
switch (value) {
case null:
return TypeName.null;
@ -102,11 +103,11 @@ function is(value: unknown): TypeName { // tslint:disable-line:only-arrow-functi
return TypeName.Observable;
}
if (Array.isArray(value)) {
if (is.array(value)) {
return TypeName.Array;
}
if (isBuffer(value)) {
if (is.buffer(value)) {
return TypeName.Buffer;
}
@ -122,25 +123,24 @@ function is(value: unknown): TypeName { // tslint:disable-line:only-arrow-functi
return TypeName.Object;
}
// tslint:disable-next-line:strict-type-predicates
// tslint:disable-next-line: strict-type-predicates
const isObject = (value: unknown): value is object => typeof value === 'object';
is.undefined = isOfType<undefined>('undefined');
is.string = isOfType<string>('string');
is.number = isOfType<number>('number');
is.function_ = isOfType<Function>('function');
// tslint:disable-next-line:strict-type-predicates
// tslint:disable-next-line: strict-type-predicates
is.null_ = (value: unknown): value is null => value === null;
is.class_ = (value: unknown): value is Class => is.function_(value) && value.toString().startsWith('class ');
is.boolean = (value: unknown): value is boolean => value === true || value === false;
is.symbol = isOfType<Symbol>('symbol');
// tslint:enable:variable-name
is.symbol = isOfType<symbol>('symbol');
is.numericString = (value: unknown): boolean =>
is.numericString = (value: unknown): value is string =>
is.string(value) && value.length > 0 && !Number.isNaN(Number(value));
is.array = Array.isArray;
is.buffer = isBuffer;
is.buffer = (value: unknown): value is Buffer => !is.nullOrUndefined(value) && !is.nullOrUndefined((value as Buffer).constructor) && is.function_((value as Buffer).constructor.isBuffer) && (value as Buffer).constructor.isBuffer(value);
is.nullOrUndefined = (value: unknown): value is null | undefined => is.null_(value) || is.undefined(value);
is.object = (value: unknown): value is object => !is.nullOrUndefined(value) && (is.function_(value) || isObject(value));
@ -188,7 +188,7 @@ is.dataView = isObjectOfType<DataView>(TypeName.DataView);
is.directInstanceOf = <T>(instance: unknown, klass: Class<T>): instance is T => Object.getPrototypeOf(instance) === klass.prototype;
is.urlInstance = (value: unknown): value is URL => isObjectOfType<URL>(TypeName.URL)(value);
is.urlString = (value: unknown) => {
is.urlString = (value: unknown): value is string => {
if (!is.string(value)) {
return false;
}
@ -201,12 +201,15 @@ is.urlString = (value: unknown) => {
}
};
// TODO: Use the `not` operator with a type guard here when it's available.
// Example: `is.truthy = (value: unknown): value is not (false | undefined | null) => Boolean(value);`
is.truthy = (value: unknown) => Boolean(value);
// Example: `is.falsy = (value: unknown): value is not (true | …) => Boolean(value);`
is.falsy = (value: unknown) => !value;
is.nan = (value: unknown) => Number.isNaN(value as number);
const primitiveTypes = new Set([
const primitiveTypeOfTypes = new Set([
'undefined',
'string',
'number',
@ -214,12 +217,12 @@ const primitiveTypes = new Set([
'symbol'
]);
is.primitive = (value: unknown): value is Primitive => is.null_(value) || primitiveTypes.has(typeof value);
is.primitive = (value: unknown): value is Primitive => is.null_(value) || primitiveTypeOfTypes.has(typeof value);
is.integer = (value: unknown): value is number => Number.isInteger(value as number);
is.safeInteger = (value: unknown): value is number => Number.isSafeInteger(value as number);
is.plainObject = (value: unknown) => {
is.plainObject = (value: unknown): value is {[key: string]: unknown} => {
// From: https://github.com/sindresorhus/is-plain-obj/blob/master/index.js
let prototype;
@ -242,7 +245,6 @@ const typedArrayTypes = new Set([
is.typedArray = (value: unknown): value is TypedArray => {
const objectType = getObjectType(value);
if (objectType === null) {
return false;
}
@ -250,10 +252,10 @@ is.typedArray = (value: unknown): value is TypedArray => {
return typedArrayTypes.has(objectType);
};
const isValidLength = (value: unknown) => is.safeInteger(value) && value > -1;
const isValidLength = (value: unknown) => is.safeInteger(value) && value >= 0;
is.arrayLike = (value: unknown): value is ArrayLike => !is.nullOrUndefined(value) && !is.function_(value) && isValidLength((value as ArrayLike).length);
is.inRange = (value: number, range: number | number[]) => {
is.inRange = (value: number, range: number | number[]): value is number => {
if (is.number(range)) {
return value >= Math.min(0, range) && value <= Math.max(range, 0);
}
@ -277,7 +279,12 @@ const DOM_PROPERTIES_TO_CHECK = [
is.domElement = (value: unknown): value is DomElement => is.object(value) && (value as DomElement).nodeType === NODE_TYPE_ELEMENT && is.string((value as DomElement).nodeName) &&
!is.plainObject(value) && DOM_PROPERTIES_TO_CHECK.every(property => property in (value as DomElement));
is.observable = (value: unknown) => {
export interface ObservableLike {
subscribe(observer: (value: unknown) => void): void;
[Symbol.observable](): ObservableLike;
}
is.observable = (value: unknown): value is ObservableLike => {
if (!value) {
return false;
}
@ -297,30 +304,34 @@ is.nodeStream = (value: unknown): value is NodeStream => !is.nullOrUndefined(val
is.infinite = (value: unknown) => value === Infinity || value === -Infinity;
const isAbsoluteMod2 = (rem: number) => (value: number) => is.integer(value) && Math.abs(value % 2) === rem;
const isAbsoluteMod2 = (rem: number) => (value: number): value is number => is.integer(value) && Math.abs(value % 2) === rem;
is.evenInteger = isAbsoluteMod2(0);
is.oddInteger = isAbsoluteMod2(1);
is.emptyArray = (value: unknown): value is never[] => is.array(value) && value.length === 0;
is.nonEmptyArray = (value: unknown): value is unknown[] => is.array(value) && value.length > 0;
is.emptyString = (value: unknown): value is string => is.string(value) && value.length === 0;
is.nonEmptyString = (value: unknown): value is string => is.string(value) && value.length > 0;
const isWhiteSpaceString = (value: unknown) => is.string(value) && /\S/.test(value) === false;
is.emptyStringOrWhitespace = (value: unknown): value is string => is.emptyString(value) || isWhiteSpaceString(value);
is.emptyArray = (value: unknown) => is.array(value) && value.length === 0;
is.nonEmptyArray = (value: unknown) => is.array(value) && value.length > 0;
is.emptyObject = (value: unknown): value is {[key: string]: never} => is.object(value) && !is.map(value) && !is.set(value) && Object.keys(value).length === 0;
is.emptyString = (value: unknown) => is.string(value) && value.length === 0;
is.nonEmptyString = (value: unknown) => is.string(value) && value.length > 0;
is.emptyStringOrWhitespace = (value: unknown) => is.emptyString(value) || isWhiteSpaceString(value);
// TODO: Use `not` operator here to remove `Map` and `Set` from type guard:
// - https://github.com/Microsoft/TypeScript/pull/29317
is.nonEmptyObject = (value: unknown): value is {[key: string]: unknown} => is.object(value) && !is.map(value) && !is.set(value) && Object.keys(value).length > 0;
is.emptyObject = (value: unknown) => is.object(value) && !is.map(value) && !is.set(value) && Object.keys(value).length === 0;
is.nonEmptyObject = (value: unknown) => is.object(value) && !is.map(value) && !is.set(value) && Object.keys(value).length > 0;
is.emptySet = (value: unknown): value is Set<never> => is.set(value) && value.size === 0;
is.nonEmptySet = (value: unknown): value is Set<unknown> => is.set(value) && value.size > 0;
is.emptySet = (value: unknown) => is.set(value) && value.size === 0;
is.nonEmptySet = (value: unknown) => is.set(value) && value.size > 0;
is.emptyMap = (value: unknown) => is.map(value) && value.size === 0;
is.nonEmptyMap = (value: unknown) => is.map(value) && value.size > 0;
is.emptyMap = (value: unknown): value is Map<never, never> => is.map(value) && value.size === 0;
is.nonEmptyMap = (value: unknown): value is Map<unknown, unknown> => is.map(value) && value.size > 0;
export type Predicate = (value: unknown) => boolean;
type ArrayMethod = (fn: (value: unknown, index: number, array: unknown[]) => boolean, thisArg?: unknown) => boolean;
const predicateOnArray = (method: ArrayMethod, predicate: unknown, values: unknown[]) => {
const predicateOnArray = (method: ArrayMethod, predicate: Predicate, values: unknown[]) => {
if (is.function_(predicate) === false) {
throw new TypeError(`Invalid predicate: ${JSON.stringify(predicate)}`);
}
@ -329,12 +340,12 @@ const predicateOnArray = (method: ArrayMethod, predicate: unknown, values: unkno
throw new TypeError('Invalid number of values');
}
return method.call(values, predicate as any);
return method.call(values, predicate);
};
// tslint:disable variable-name
is.any = (predicate: unknown, ...values: unknown[]) => predicateOnArray(Array.prototype.some, predicate, values);
is.all = (predicate: unknown, ...values: unknown[]) => predicateOnArray(Array.prototype.every, predicate, values);
is.any = (predicate: Predicate, ...values: unknown[]): boolean => predicateOnArray(Array.prototype.some, predicate, values);
is.all = (predicate: Predicate, ...values: unknown[]): boolean => predicateOnArray(Array.prototype.every, predicate, values);
// tslint:enable variable-name
// Some few keywords are reserved, but we'll populate them for Node.js users

4
source/tests/test.ts
View file

@ -867,7 +867,7 @@ test('is.any', t => {
t.false(is.any(is.integer, true, 'lol', {}));
t.throws(() => {
is.any(null, true);
is.any(null as any, true);
});
t.throws(() => {
@ -882,7 +882,7 @@ test('is.all', t => {
t.false(is.all(is.set, new Map(), {}));
t.throws(() => {
is.all(null, true);
is.all(null as any, true);
});
t.throws(() => {

5
tslint.json
View file

@ -1,3 +1,6 @@
{
"extends": "tslint-xo"
"extends": "tslint-xo",
"rules": {
"interface-over-type-literal": false
}
}