JavaScript Fundaments

is.js

function is(value) {
  const checks = {
    get string() {
      return value instanceof String || typeof value === "string";
    },
    get undefined() {
      return typeof value === "undefined" || value === undefined;
    },
    get null() {
      return value === null;
    },
    get symbol() {
      return typeof value === "symbol";
    },
    get number() {
      return typeof value === "number" || value instanceof Number;
    },
    get boolean() {
      return typeof value === "boolean" || value instanceof Boolean;
    },
    get array() {
      return value instanceof Array;
    },
    get object() {
      return value && value.constructor === Object ? true : false;
    },
    get function() {
      return typeof value === "function";
    },
    get boundFunction() {
      // Since bind() method returns a new function without prototype we can simply check
      // if it has a prototype or not
      // NOTE: both arrow functions and bound functions do not have a prototype
      return this.function && value.prototype ? false : true;
    },
    get bigInt() {
      return typeof value === "bigint" || value instanceof BigInt;
    },
    get numericString() {
      // Notice how we can resuse existing getters
      return this.string && Number(value) ? true : false;
    },
    get date() {
      return value instanceof Date && !isNaN(value);
    },
    get regExp() {
      return value instanceof RegExp;
    },
    get error() {
      return value instanceof Error;
    },
    get promise() {
      return value instanceof Promise;
    },
    get truthy() {
      // Pretty Neat, Right?
      return !!value;
    },
    get falsy() {
      return !value;
    },
    get set() {
      // this is the only check required since there are no set literals in javascript
      return value instanceof Set;
    },

    get map() {
      // this is the only check required since there are no map literals in javascript
      return value instanceof Map;
    },
    get iteratable() {
      // reference - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
      return Symbol.iterator in Object(value);
    },
  };
  return new Proxy(checks, {
    get(target, name) {
      if (target[name] !== undefined) return target[name];
      throw new Error("Property Does not exist!");
    },
  });
}

console.log(is("Malik").asdsdadadd)