Currently I am doing some stuff in JavaScript and I need to have just a tiny amounts of code to work with. As tiny as this article. But there are some things I really need to make the development comfortable for myself. So I require them to be tiny too.
Two-Liner Each (one function)
Works just with objects and arrays. For objects, callback takes key and value. For arrays, callback takes element.
/**
* Tiny each
* @param {Array, Object} iterable the iterable to iterate through
* @param {Function} func to call on each iteration, in array-mode gets an element (func(elem)),
in object-mode gets a key and value (func(v, k))
*/
function each(iterable, func) {
if (iterable instanceof Array) for (var i = 0; i < iterable.length; i++) func.call(iterable, iterable[i]);
else if (iterable instanceof Object) for (field in iterable) func.call(iterable, iterable[field], field);
}
Quick Class Construction (Single Inheritance, one function)
This is just a slightly modified version from this nice article. Also, bind function is useful to make stuff like this: var catMeow = bind(cat, Cat.meow);.
function class_(def) {
var _proto = def;
if (def['_extends'] !== undefined) {
var _ex = def['_extends'];
if (typeof _ex === 'function') {
each(_ex.prototype, function(v, k){
if (_proto[k] === undefined) {
_proto[k] = v;
} else {
_proto['_s_'+k] = v;
}
});
} else throw new Error('Wrong _extends field');
}
var _init = def['_init'];
if (_init === undefined) {
_init = function() {
if (this.prototype['_s__init']) this._init_super();
}
}
_init.prototype = _proto;
def['hasOwnProperty'] = function(k) {
return (k !== 'hasOwnProperty')
&& (Object.prototype.hasOwnProperty.call(this, k)
|| Object.prototype.hasOwnProperty.call(_proto, k));
}
return _init;
}
function bind(obj, method) {
return function() { return method.apply(obj, arguments); }
}
Usage
var Base = class_({
_init: function(a, b) {
this.a = a;
this.b = b;
}
someMethod: function() {
console.log('parent');
}
});
var Child = class_({
_extends: Base,
_init: function(c) {
this._s__init(5, 6);
this.c = 7;
console.log(this.a);
console.log(this.b);
console.log(this.c);
},
someMethod: function() {
this._s_someMethod();
console.log('child');
}
});
var b = new Base();
var c = new Child();
b.someMethod();
c.someMethod();
console.log(b instanceof Base);
console.log(b instanceof Child);
console.log(c instanceof Base);
console.log(c instanceof Child);
Easy assertions mechanism (one or two functions)
Just for quick TDD, if you like it. If you need only assertions, not a tests suites, take just AssertException and assert function - they are everything you need. Else, runTests allows you to run JUnit-like tests suites, even with proper setUp and tearDown. (Uses console to inform about tests results so in the presented form it may work only in Firefox / WebKit browsers)
function AssertException(result, expectation) { this.result = result;
this.expectation = expectation; }
AssertException.prototype.toString = function () {
if (this.expectation) return ('AssertException: Expected: ' + this.expectation + ' Got: ' + this.result);
else return ('AssertException: Got: ' + this.result);
}
/**
* Tiny assert
* @param {Boolean} test the expression to test
* @param {String} [_expectation] what was expected
* @throws {AssertException} if assertion was failed
*/
function assert(test, _expectation) {
if (!test) throw new AssertException(test, _expectation);
}
function _assert(test, val, expectation) {
if (!test) throw new AssertException(val, expectation);
}
function assertNotNull(test) { _assert(test !== null, test + ' == null', 'not null'); }
function assertDefined(test) { _assert(test !== undefined, test + ' !== undefined', 'defined'); }
function assertTrue(test) { _assert(test, test + ' != true', 'true'); }
function assertFalse(test) { _assert(!test, test + ' != false', 'false'); }
function assertEquals(first, second) { _assert(first === second, first + ' != ' + second, second + ' == ' + second); }
function assertInstance(test, cls) { _assert(test instanceof cls, test + ' not instance of ' + cls, test + ' instance of ' + cls); }
function assertType(test, typename) { _assert(typeof test == typename, test + ' is not of type ' + typename, test + ' has type ' + typename); }
/**
* Tests runner
* @param {Object, Function} suite for function-typed parameter,
calls a function and informs through Firebug console about assertions
for object-typed parameter,
works like JUnit, calls every method which name starts with 'test...'
also calls 'setUp' and 'tearDown' in the proper moments
informs through Firebug console about assertions and passed/failed methods
* @param {String} [_name] some name for test case or test suite (used only in logs to help you determine what failed)
* @param {String} [_stopWhenFailed] for object-mode, stops testing when first assertion is failed in some method
* @returns {AssertException} first failed exception for function-mode, nothing for object-mode
*
* runTests(new SomeClass());
* runTests(someFunc(), 'someFunc');
*/
var __tCount = 0,
__fCount = 0;
function runTests(suite, _name, _stopWhenFailed) {
if (typeof suite === 'function') { __fCount++;
var field = (_name ? _name : ('Function ' + __fCount));
try { suite();
console.info('%s: %s', field, 'OK');
} catch (ex) {
if (ex instanceof AssertException) {
var info_ = '(' + field;
if (ex.lineNumber) info_ += ':' + ex.lineNumber;
if (ex.expectation) console.error('Assertion failed. Expected:', ex.expectation,
'. Got:', ex.result, info_ + ')');
else console.error('Assertion failed. Got:', ex.result, info_ + ')');
console.error(ex);
console.warn('%s: %s', field, 'FAILED');
return ex;
} else {
throw new Error(ex.toString());
}
}
} else if (typeof suite === 'object') { __tCount++;
var title = _name || ("Suite " + __tCount);
console.group(title);
for (var field in suite) {
if ((typeof suite[field] === 'function') &&
(field.indexOf('test') === 0) && suite.hasOwnProperty(field)) {
console.log('Running', title + ' / ' + field);
if (suite.setUp) suite.setUp();
var result = runTests(bind(suite, suite[field]), field);
var passed = (result === null);
if (_stopWhenFailed && (result !== null)) return result;
if (suite.tearDown) suite.tearDown();
}
}
console.groupEnd();
} else {
throw new Exception('Passed var has invalid type');
}
return null;
}
Examples
var T1 = class_({
_init: function() { },
setUp: function() { },
test1: function() {
assert(null == null);
assert(12 == null, '12 == null');
assert('a' == null);
assertTrue(true);
assertFalse(false);
assertTrue(false);
assertFalse(true);
assertEquals(5, 5.1);
assertEquals(5, 5);
assertEquals('a', 'ab');
assertEquals('a', 'a');
assertType(12, 'integer');
assertType(12, 'string');
assertType('12', 'string');
assertInstance(this, T1);
assertInstance(this, Object);
assertInstance(null, Object);
assertNotNull(this);
assertNotNull(null);
},
test2: function() {
//throw new Error('Alala');
assertEquals(6, 7.2);
},
tearDown: function() { }
});
var _f = function() {
assertTrue(true);
assertEquals('12', true);
}
runTests(new T1());
runTests(_f, '_f');
new T1().test1();
_f();
Snippets tests
Using TDD-snippet, I wrote a general Test Suite for all of three snippets to demonstrate their interaction.