Boolean.isTrue.isFalse.js

/**
 *  `Boolean.isTrue` / `Boolean.isFalse` is a fun implementation of Smalltalk's [https://en.wikipedia.org/wiki/Smalltalk]
 *  `ifTrue` / `ifFalse` control structures [https://en.wikipedia.org/wiki/Smalltalk#Control_structures].
 *
 *  It is nothing one would really desire in JavaScript unless one is looking for an alternative to its native `if...else` 
 *  statement and has deeply fallen in love with using function expressions all along.
 *
 *  EN: [https://en.wikipedia.org/wiki/Smalltalk#Control_structures]
 *  DE: [https://de.wikipedia.org/wiki/Smalltalk_(Programmiersprache)#IF-Anweisung]
 */

/**
 *  The following gist implementation is due to a recently asked question on StackOverflow ...
 *  [https://stackoverflow.com/questions/63709001/alternative-approaches-to-multiple-if-else-conditions]
 *  ... which reads *"alternative approaches to multiple if else conditions"*.
 *
 *  Someone was contributing a solution/approach for *"the most over-engineered solution" contest* ...
 *  [https://stackoverflow.com/questions/63709001/alternative-approaches-to-multiple-if-else-conditions/63709274#63709274]
 *
 *  In order to respond to and counter it a 10 year old code base needed to be revitalized and polished up ...
 *  ... [https://github.com/petsel/javascript-api-extensions/blob/master/core/smalltalk-inspired-control-structures/Boolean.ifTrue.ifFalse.js]
 */

(function (Boolean, Array, Object) {

  const boolPrototype = Boolean.prototype;
  const FUNCTION_TYPE = (typeof Boolean);

  function isFunction(type) {
    return (
         (typeof type == FUNCTION_TYPE)
      && (typeof type.call == FUNCTION_TYPE)
      && (typeof type.apply == FUNCTION_TYPE)
    );
  }
  const isArray = Array.isArray;
  const arrayFrom = Array.from;

  function getSanitizedRestArgs(args) {
    args = arrayFrom(args).slice(2);

    if ((args.length === 1) && isArray(args[0]))  {
      args = args.flat();
    }
    return args;
  }
  function getSanitizedTarget(target) {
    /* eslint-disable */
    /* jshint ignore:start */
    /* ignore jslint start */

    /* no-eq-null */
    return ((target != null) && target) || null;

    /* ignore jslint end */
    /* jshint ignore:end */
    /* eslint-enable */
  }

  /**
   *  The reason for introducing `getSanitizedRestArgs` is to achieve a unified
   *  and more convinient handling of how to pass and handle/interpret the
   *  additionally passed (rest) arguments.
   *
   *  e.g.
   *  (true).isTrue((...args) => console.log(args), null, 5, 6, 7, 8);    // expect: [5, 6, 7, 8]
   *  (true).isTrue((...args) => console.log(args), null, [5, 6, 7, 8]);  // expect: [5, 6, 7, 8]
   *
   *  (true).isTrue((...args) => console.log(args), null, [5, 6, [5, 6, 7, 8], 7, 8]);  // expect: [5, 6, [5, 6, 7, 8], 7, 8]
   *  (true).isTrue((...args) => console.log(args), null, 5, 6, [5, 6, 7, 8], 7, 8);    // expect: [5, 6, [5, 6, 7, 8], 7, 8]
   */

  function isTrue(handler, target/*, ...args*/) {
    const isTrue = this.valueOf();
    if (isTrue && isFunction(handler)) {

      // handler.apply(getSanitizedTarget(target), args.flat()); // does not meet the goal.
      handler.apply(getSanitizedTarget(target), getSanitizedRestArgs(arguments));
    }
    return isTrue;
  }
  // isTrue.toString = () => 'isTrue() { [native code] }';
  // isTrue.toString = () => 'true() { [native code] }';

  function isFalse(handler, target/*, ...args*/) {
    const isTrue = this.valueOf();
    if (!isTrue && isFunction(handler)) {

      // handler.apply(getSanitizedTarget(target), args.flat()); // does not meet the goal.
      handler.apply(getSanitizedTarget(target), getSanitizedRestArgs(arguments));
    }
    return isTrue;
  }
  // isFalse.toString = () => 'isFalse() { [native code] }';
  // isFalse.toString = () => 'false() { [native code] }';

  Object.defineProperty(boolPrototype, 'isTrue', {
  // Object.defineProperty(boolPrototype, 'true', {
    configurable: true,
    writable: true,
    value: isTrue
  });

  Object.defineProperty(boolPrototype, 'isFalse', {
  // Object.defineProperty(boolPrototype, 'false', {
    configurable: true,
    writable: true,
    value: isFalse
  });

}(Boolean, Array, Object));

Boolean.isTrue.isFalse.simple.test.js

// proof of concept in coming up with the likely most over-engineered approach answering a Q. on StackOverflow
// [https://stackoverflow.com/questions/63709001/alternative-approaches-to-multiple-if-else-conditions]

function assignTableName(name) {
    table_name = name;
}
let table_name = "";

let date, currentDate, source;
let isCurrent, isS3;


// test for 'Table4'
//
date = '* now *';
currentDate = 'now';
source = '* s3 *'

isCurrent = (date === currentDate);
isS3 = (source === 's3');

isCurrent
  .isTrue(() => isS3
    .isTrue(assignTableName, null, 'Table1')
    .isFalse(assignTableName, null, 'Table2')
  )
  .isFalse(() => isS3
    .isTrue(assignTableName, null, 'Table3')
    .isFalse(assignTableName, null, 'Table4')
  );

console.log(table_name);


// test for 'Table3'
//
date = '* now *';
currentDate = 'now';
source = 's3'

isCurrent = (date === currentDate);
isS3 = (source === 's3');

isCurrent
  .isTrue(() => isS3
    .isTrue(assignTableName, null, 'Table1')
    .isFalse(assignTableName, null, 'Table2')
  )
  .isFalse(() => isS3
    .isTrue(assignTableName, null, 'Table3')
    .isFalse(assignTableName, null, 'Table4')
  );

console.log(table_name);


// test for 'Table1'
//
date = 'now';
currentDate = 'now';
source = 's3'

isCurrent = (date === currentDate);
isS3 = (source === 's3');

isCurrent
  .isTrue(() => isS3
    .isTrue(assignTableName, null, 'Table1')
    .isFalse(assignTableName, null, 'Table2')
  )
  .isFalse(() => isS3
    .isTrue(assignTableName, null, 'Table3')
    .isFalse(assignTableName, null, 'Table4')
  );

console.log(table_name);


// test for 'Table2'
//
date = 'now';
currentDate = 'now';
source = '* s3 *'

isCurrent = (date === currentDate);
isS3 = (source === 's3');

isCurrent
  .isTrue(() => isS3
    .isTrue(assignTableName, null, 'Table1')
    .isFalse(assignTableName, null, 'Table2')
  )
  .isFalse(() => isS3
    .isTrue(assignTableName, null, 'Table3')
    .isFalse(assignTableName, null, 'Table4')
  );

console.log(table_name);

Haha, you definitely won the contest 😄

Haha, you definitely won the contest 😄

Thanks, it means a lot to me. I accept the honor.