Objects drills

text

1.) Object creator drill

function createMyObject() {
  return {
    foo: "bar",
    answerToUniverse: 42,
    "olly olly": "oxen free",
    sayHello: function() {
       return "hello";
     }
};
}


/* From here down, you are not expected to 
   understand.... for now :)     
*/

(function testCreateMyObject() {
  var obj = createMyObject();
  if (typeof obj !== 'object') {
    console.error('ERROR: `createMyObject` must return an object');
    return false;
  }
  var expectedKeys = ['foo', 'answerToUniverse', 'olly olly', 'sayHello'];
  expectedKeys.forEach(function(key) {
    if (!(key in obj)) {
      console.error('ERROR: Missing a key for ' + key);
      return false;
    }
  });
  if (obj.foo !== 'bar') {
    console.error("ERROR: Value for `foo` should be 'bar' but was " + obj.foo);
    return false;
  }
  if (obj.answerToUniverse !== 42) {
    console.error(
      'ERROR: Value for `answerToUniverse` should be 42 but was ' +
        obj.answerToUniverse
    );
    return false;
  }
  if (obj['olly olly'] !== 'oxen free') {
    console.error(
      "ERROR: Value for `'olly olly'` should be 'oxen free' but was " +
        obj['olly olly']
    );
    return false;
  }
  if (!(typeof obj.sayHello === 'function' && obj.sayHello() === 'hello')) {
    console.error(
      "ERROR: Value for `sayHello` must be a function that returns the string 'hello'"
    );
    return false;
  }
  console.log('SUCCESS: Your function works!');
})();



2.) Object updater drill

function updateObject(obj) {
  obj.foo = 'foo';
  obj.bar = 'bar';
  obj.bizz = 'bizz';
  obj.bang = 'bang';
  return obj;
}



/* From here down, you are not expected to 
   understand.... for now :)  
   
   
   Nothing to see here!
   
*/

(function testUpdateObject() {
  var oldObj = {
    cats: 'cats',
    dogs: 'dogs',
  };
  var newObj = updateObject(oldObj);
  if (typeof newObj !== 'object') { 
    console.error('ERROR: `createMyObject` must return an object');
    return false
  }
  ['foo', 'bar', 'bizz', 'bang'].forEach(function(key) {
    if (!(key in newObj)) {
      console.error('ERROR: `' + key + '` not in object returned by `updateObject`');
      return false;
    }
  });
  ['foo', 'bar', 'bizz', 'bang'].forEach(function(key) {
    if (newObj[key] !== key) {
      console.error('ERROR: `' + key + '` should be "' + key + '" but was ' + newObj[key]);
      return false;
    }
  });
  if (!(newObj.cats === 'cats' && newObj.dogs === 'dogs')) {
    console.error('ERROR: your function doesn\'t preserve existing key/value pairs');
    return false;
  }
  console.log('SUCCESS: `updateObject` works correctly!');
  
})();



3.) Self-reference drill

function personMaker() {
  var person = {
    firstName: 'Paul',
    lastName: 'Jones',
    fullName: function() {
      return this.firstName + " " + this.lastName;
    }
  };
  return person;
}

/* From here down, you are not expected to 
   understand.... for now :)  
   
   
   Nothing to see here!
   
*/

(function testPersonMaker() {
  var person = personMaker();
  if (typeof person !== 'object') {
    console.error('ERROR: `personMaker` must return an object');
    return false;
  }
  if (typeof person.fullName !== 'function') {
    console.error('ERROR: `fullName` must be a method');
    return false;
  }
  if (person.fullName() !== 'Paul Jones') {
    console.error(
      'ERROR: The value for `fullName` should be "Paul Jones" but was ' +
        person.fullName()
    );
    return false;
  }
  person.firstName = 'Lisa';
  person.lastName = 'Simpson';
  if (person.fullName() !== 'Lisa Simpson') {
    console.error(
      '`personMaker` is not using self reference correctly. ' +
        'When firstName set to "Lisa" and lastName set to "Simpson", ' +
        'should return "Lisa Simpson" but returned ' +
        person.fullName()
    );
  }
  console.log('SUCCESS: `updateObject` works correctly!');
})();



4.) Deleting keys drill


var sampleObj = {
  foo: 'foo',
  bar: 'bar',
  bizz: 'bizz',
  bang: 'bang',
};

function keyDeleter(obj) {
  delete obj.foo;
  delete obj.bar;
  return obj;
}



/* From here down, you are not expected to 
   understand.... for now :)  
   
   
   Nothing to see here!
   
*/

(function testKeyDeleter() {
  var obj = keyDeleter({
    foo: 'foo',
    bar: 'bar',
    bizz: 'bizz',
    bang: 'bang',
  });

  if (typeof obj !== 'object') {
    console.error('ERROR: `keyDeleter` must be return an object');
    return false;
  }
  ['foo', 'bar'].forEach(function(key) {
    if (key in obj) {
      console.error('`keyDeleter` did not delete the key for ' + key);
      return false;
    }
  });
  ['bizz', 'bang'].forEach(function(key) {
    if (!(key in obj && obj[key] === key)) {
      console.error('`keyDeleter` is deleting keys other than `foo` and `bar`');
      return false;
    }
  });
  console.log('SUCCESS: `keyDeleter` works correctly!');
})();