Package Exports

is-like
is-like/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (is-like) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

is-like

Functions to check if a value is something alike.

Install

Node.js

npm i is-like

Deno

import { isDictLike, isArrayLike, /* ... */ } from "https://deno.land/x/is_like/index.js";
// Or
import { isDictLike, isArrayLike, /* ... */ } from "https://github.com/ayonli/is-like/raw/master/index.js";

API

Currently, this module includes the following functions.

`isDictLike(value: any): boolean`

Checks if the input value is a dict object, which includes key-value pairs.

console.assert(isDictLike({}));
console.assert(isDictLike({ foo: "bar" }));

class Test {
    constructor(name) {
        this.name = name;
    }
}
console.assert(isDictLike(new Test("Test")));
console.assert(!isDictLike(new Test())); // an empty custom object will fail

console.assert(!isDictLike(new Date()));
console.assert(!isDictLike(/[a-z]/));
console.assert(!isDictLike(["hello", "world"]));
console.assert(!isDictLike(new Map([["foo", "Hello"], ["bar", "World"]])));
console.assert(!isDictLike(new Error("something went wrong")));
console.assert(!isDictLike(Buffer.from("Hello, World!")));
console.assert(!isDictLike(Promise.resolve("Hello, World!")));

`isArrayLike(value: any): boolean`

Checks if the input value is an object with length property or a string.

console.assert(isArrayLike([1, 2, 3]));
console.assert(isArrayLike(Int8Array.from([1, 2, 3])));
console.assert(isArrayLike(Uint8Array.from([1, 2, 3])));
console.assert(isArrayLike(Int16Array.from([1, 2, 3])));
console.assert(isArrayLike(Uint16Array.from([1, 2, 3])));
console.assert(isArrayLike(Int32Array.from([1, 2, 3])));
console.assert(isArrayLike(Uint32Array.from([1, 2, 3])));
console.assert(isArrayLike(Float32Array.from([1, 2, 3])));
console.assert(isArrayLike(Float64Array.from([1, 2, 3])));
console.assert(isArrayLike(Buffer.from([1, 2, 3])));

let args = null;
(function () { args = arguments; })("Hello, World!");
console.assert(isArrayLike(args));

console.assert(isArrayLike("Hello, World!"));
console.assert(isArrayLike(new String("Hello, World!")));

class MyArray extends Array { }
console.assert(isArrayLike(new MyArray(8)));

class ArrayLike {
    get length() {
        return 0;
    }
    [Symbol.iterator]() { }
}
console.assert(isArrayLike(new ArrayLike()));

`isCollectionLike(value: any, excludeWeakOnes?: boolean): boolean`

Checks if the input value is an object with size property and [Symbol.iterator]() method, or is an instance of WeakMap or WeakSet if excludeWeakOnes is not set.

console.assert(isCollectionLike(new Map));
console.assert(isCollectionLike(new Set));
console.assert(isCollectionLike(new WeakMap));
console.assert(!isCollectionLike(new WeakMap, true));
console.assert(isCollectionLike(new WeakSet));
console.assert(!isCollectionLike(new WeakSet, true));

class MyMap extends Map { }
console.assert(isCollectionLike(new MyMap));

class MySet extends Set { }
console.assert(isCollectionLike(new MySet));

class CollectionLike {
    get size() {
        return 0;
    }
    [Symbol.iterator]() { }
}
console.assert(isCollectionLike(new CollectionLike));

`isTypedArrayLike(value: any): boolean`

Checks if the input value is an object with byteLength property and slice() method.

Alias: isBufferLike, deprecated.

console.assert(isTypedArrayLike(Buffer.from([1, 2, 3])));
console.assert(isTypedArrayLike(new ArrayBuffer(8)));
console.assert(isTypedArrayLike(Int8Array.from([1, 2, 3])));
console.assert(isTypedArrayLike(Uint8Array.from([1, 2, 3])));
console.assert(isTypedArrayLike(Int16Array.from([1, 2, 3])));
console.assert(isTypedArrayLike(Uint16Array.from([1, 2, 3])));
console.assert(isTypedArrayLike(Int32Array.from([1, 2, 3])));
console.assert(isTypedArrayLike(Uint32Array.from([1, 2, 3])));
console.assert(isTypedArrayLike(Float32Array.from([1, 2, 3])));
console.assert(isTypedArrayLike(Float64Array.from([1, 2, 3])));

`isErrorLike(value: any): boolean`

Checks if the input value is an object with name, message and stack properties.

console.assert(isErrorLike(new Error("something went wrong")));
console.assert(isErrorLike(new EvalError("something went wrong")));
console.assert(isErrorLike(new RangeError("something went wrong")));
console.assert(isErrorLike(new RangeError("something went wrong")));
console.assert(isErrorLike(new ReferenceError("something went wrong")));
console.assert(isErrorLike(new SyntaxError("something went wrong")));
console.assert(isErrorLike(new TypeError("something went wrong")));
console.assert(isErrorLike(new URIError("something went wrong")));
console.assert(isErrorLike(new assert.AssertionError({ message: "something went wrong" })));

class MyError extends Error { }
console.assert(isErrorLike(new MyError("something went wrong")));

let err = { name: "CustomError", message: "something went wrong" };
Error.captureStackTrace(err);
console.assert(isErrorLike(err));

`isPromiseLike(value: any): boolean`

Checks if the input is an object with then() method.

console.assert(isPromiseLike(Promise.resolve(123)));
console.assert(isPromiseLike({ then() { } }));
console.assert(isPromiseLike({ then: () => { } }));
console.assert(!isPromiseLike({ then: 123 }));