jizy-utils/lib/js/types.js

A simple JS utility library.

const Types = {};

Types.isNull = (x) => x === null;

Types.isUndefined = (x) => x === undefined;

Types.isNil = (x) => Types.isNull(x) || Types.isUndefined(x);

// check for strings and string literal type. e.g: 's', "s", `str`, new String()
Types.isString = (x) => !Types.isNil(x) && (typeof x === 'string' || x instanceof String);

// check for number or number literal type. e.g: 12, 30.5, new Number()
Types.isNumber = (x) => !Types.isNil(x) && ((!isNaN(x) && isFinite(x) && typeof x === 'number') || x instanceof Number);

// check for boolean or boolean literal type. e.g: true, false, new Boolean()
Types.isBoolean = (x) => !Types.isNil(x) && (typeof x === 'boolean' || x instanceof Boolean);

Types.isArray = (x) => !Types.isNil(x) && Array.isArray(x);

// check for object or object literal type. e.g: {}, new Object(), Object.create(null)
Types.isObject = (x) => !Types.isNil(x) && ({}).toString.call(x) === '[object Object]';

// check for provided type instance
Types.is = (x, X) => !Types.isNil(x) && x instanceof X;
Types.isSet = (x) => Types.is(x, Set);
Types.isMap = (x) => Types.is(x, Map);
Types.isDate = (x) => Types.is(x, Date);

// check for provided type
Types.isA = (x, X) => !Types.isNil(x) && typeof x === X;
Types.isFunction = (x) => Types.isA(x, 'function');

Types.isWindow = (x) => {
    return Types.isObject(x) && x == x.window;
}

Types.isDocument = (x) => {
    return Types.isObject(x) && x.nodeType == x.DOCUMENT_NODE;
}

Types.isPlainObject = (x) => {
    return Types.isObject(x) && !Types.isWindow(x) && Object.getPrototypeOf(x) == Object.prototype;
}

Types.isEmptyObject = (x) => {
    return Types.isObject(x) && Object.keys(x).length === 0;
}

Types.likeArray = (x) => {
    const length = !!x && 'length' in x && x.length;

    return !Types.isFunction(x) && !Types.isWindow(x) && (
        Array.isArray(x) || length === 0 || (Types.isNumber(length) && length > 0 && (length - 1) in x)
    );
}

export default Types;