Checker.js - truthy, falsey & equality comparisons simplified.

README.md

Checker.js

• Waterfall checks for:
  • truthiness
  • falseyness
  • equality
• Perks
  • built-in argument iteration support for .t() and .f()
  • built-in pairwise iteration support for .eq() and ineq
  • uses fast-deep equal for .eq() and ineq()
  • .can().be().chained()
  • just call .check() at the end
  • Returns the result of function / promise

Sample 1:

Executes given functions

new Checker()
  .t(1, true)
  .f(0, false)
  .eq(1,1,1,1)
  .ineq(1,2)
  .pass(() => {
    console.log('pass');
  })
  .fail(() => {
  	console.log('fail');
  })
  .check();

// pass

Sample 2:

Returns a promise, makes it chainable with then.

new Checker()
  .t(1, true)
  .f(0, false)
  .eq(1,1,1)
  .ineq(1,2)
  .pass(() => Promise.resolve('pass'))
  .fail(() => Promise.reject('fail'))
  .check()
  .then(() => {
  	console.log('passed!');
  })
  .catch(() => {
  	console.error('failed!');
  });

// passed!

Checker.js

class Checker{
	constructor () {
  	this._passed = true;
  }
  static pairwise (list) {
  	// https://codereview.stackexchange.com/a/75667
    let pairs = new Array((list.length * (list.length - 1)) / 2);
    let pos = 0;
    for (let i = 0; i < list.length; i++) {
      for (let j = i + 1; j < list.length; j++) {
        pairs[pos++] = [list[i], list[j]];
      }
    }
    return pairs;
  }
  static equal (a, b) {
    // https://github.com/epoberezkin/fast-deep-equal
    let isArray = Array.isArray;
    let keyList = Object.keys;
    let hasProp = Object.prototype.hasOwnProperty;
    if (a === b) return true;
    let arrA = isArray(a), arrB = isArray(b), i, length, key;
    if (arrA && arrB) {
      length = a.length;
      if (length != b.length) return false;
      for (i = 0; i < length; i++)
        if (!equal(a[i], b[i])) return false;
      return true;
    }
    if (arrA != arrB) return false;
    let dateA = a instanceof Date, dateB = b instanceof Date;
    if (dateA != dateB) return false;
    if (dateA && dateB) return a.getTime() == b.getTime();
    let regexpA = a instanceof RegExp, regexpB = b instanceof RegExp;
    if (regexpA != regexpB) return false;
    if (regexpA && regexpB) return a.toString() == b.toString();
    if (a instanceof Object && b instanceof Object) {
      let keys = keyList(a);
      length = keys.length;
      if (length !== keyList(b).length)
        return false;
      for (i = 0; i < length; i++)
        if (!hasProp.call(b, keys[i])) return false;
      for (i = 0; i < length; i++) {
        key = keys[i];
        if (!equal(a[key], b[key])) return false;
      }
      return true;
    }
    return false;
  }
  t (...args) {
  	let instance = this;
  	args.map((arg) => {
    	if (Boolean(arg) === false) {
      	instance._passed = false;
      }
    });
  	return this;
  }
  f (...args) {
  	let instance = this;
  	args.map((arg) => {
    	if (Boolean(arg) === true) {
      	instance._passed = false;
      }
    });
  	return this;
  }
  eq (...args) {
  	let instance = this;    
    let pairs = Checker.pairwise(args);
    pairs.map((pair) => {
    	if (Checker.equal.apply(null, pair) === false) {
      	instance._passed = false;
      }
    });
  	return this;
  }
  ineq (...args) {
  	let instance = this;    
    let pairs = Checker.pairwise(args);
    pairs.map((pair) => {
    	if (Checker.equal.apply(null, pair) === true) {
      	instance._passed = false;
      }
    });
  	return this;
  }
  pass (fn) {
  	this._passFn = fn;
    return this;
  }
  fail (fn) {
  	this._failFn = fn;
    return this;
  }
  check () {
  	if (this._passed === true) {
    	return this._passFn();
    } else {
    	return this._failFn();
    }
  }
}

To add:

xi() for parseInt()
xf() for parseFloat()
xs() for toString()