ts-type-guards/dist/is.mjs

Curried TypeScript type guards for primitive types and classes

const TYPE_GUARDS_PRIMITIVE = [isBoolean, isNumber, isString, isSymbol, isNull, isUndefined];
export function isBoolean(x) {
    return typeof x === "boolean";
}
export function isBooleanLike(x) {
    return isBoolean(x) || is(Boolean)(x);
}
export function isNumber(x) {
    return typeof x === "number";
}
export function isNumberLike(x) {
    return isNumber(x) || is(Number)(x);
}
export function isString(x) {
    return typeof x === "string";
}
export function isStringLike(x) {
    return isString(x) || is(String)(x);
}
export function isSymbol(x) {
    return typeof x === "symbol";
}
export function isNull(x) {
    return x === null;
}
export function isUndefined(x) {
    return x === undefined;
}
export function isNothing(x) {
    return x === null || x === undefined;
}
export function isSomething(x) {
    return !isNothing(x);
}
export function isPrimitive(x) {
    return TYPE_GUARDS_PRIMITIVE.some(f => f(x));
}
export function isNonPrimitive(x) {
    return !isPrimitive(x);
}
function namedFunction(name, fun) {
    return Object.defineProperty(fun, "name", { value: name, writable: false });
}
function namedTypeGuard(creator, type, typeGuard) {
    return namedFunction(`${creator.name}(${type.name})`, typeGuard);
}
export function is(type) {
    if (isPrimitive(type)) {
        return (_) => false;
    }
    return namedTypeGuard(is, type, (x) => x instanceof type);
}
export function isLike(reference) {
    for (const f of TYPE_GUARDS_PRIMITIVE) {
        if (f(reference)) {
            return (x) => f(x);
        }
    }
    if (is(Array)(reference)) {
        return (x) => is(Array)(x) && (reference.length > 0 ? x.every(isLike(reference[0])) : true);
    }
    if (reference.constructor === Object) {
        return (x) => (isSomething(x)
            &&
                Object.keys(reference).every(k => isLike(reference[k])(x[k])));
    }
    if (reference.constructor instanceof Function) {
        return is(reference.constructor);
    }
    throw new TypeError(isLike.name + ` cannot use this object as reference because it has no constructor: ` + JSON.stringify(reference));
}
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