freecodecamp: Wherefore art thou

objFilter.md

Description

Make a function that looks through an array of objects (first argument) and returns an array of all objects that have matching name and value pairs (second argument). Each name and value pair of the source object has to be present in the object from the collection if it is to be included in the returned array. For example, if the first argument is [{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last: null }, { first: "Tybalt", last: "Capulet" }], and the second argument is { last: "Capulet" }, then you must return the third object from the array (the first argument), because it contains the name and its value, that was passed on as the second argument.

Tests

tests:
  - text: '<code>whatIsInAName([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last: null }, { first: "Tybalt", last: "Capulet" }], { last: "Capulet" })</code> should return <code>[{ first: "Tybalt", last: "Capulet" }]</code>.'
    testString: 'assert.deepEqual(whatIsInAName([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last: null }, { first: "Tybalt", last: "Capulet" }], { last: "Capulet" }), [{ first: "Tybalt", last: "Capulet" }]);'
  - text: '<code>whatIsInAName([{ "apple": 1 }, { "apple": 1 }, { "apple": 1, "bat": 2 }], { "apple": 1 })</code> should return <code>[{ "apple": 1 }, { "apple": 1 }, { "apple": 1, "bat": 2 }]</code>.'
    testString: 'assert.deepEqual(whatIsInAName([{ "apple": 1 }, { "apple": 1 }, { "apple": 1, "bat": 2 }], { "apple": 1 }), [{ "apple": 1 }, { "apple": 1 }, { "apple": 1, "bat": 2 }]);'
  - text: '<code>whatIsInAName([{ "apple": 1, "bat": 2 }, { "bat": 2 }, { "apple": 1, "bat": 2, "cookie": 2 }], { "apple": 1, "bat": 2 })</code> should return <code>[{ "apple": 1, "bat": 2 }, { "apple": 1, "bat": 2, "cookie": 2 }]</code>.'
    testString: 'assert.deepEqual(whatIsInAName([{ "apple": 1, "bat": 2 }, { "bat": 2 }, { "apple": 1, "bat": 2, "cookie": 2 }], { "apple": 1, "bat": 2 }), [{ "apple": 1, "bat": 2 }, { "apple": 1, "bat": 2, "cookie": 2 }]);'
  - text: '<code>whatIsInAName([{ "apple": 1, "bat": 2 }, { "apple": 1 }, { "apple": 1, "bat": 2, "cookie": 2 }], { "apple": 1, "cookie": 2 })</code> should return <code>[{ "apple": 1, "bat": 2, "cookie": 2 }]</code>.'
    testString: 'assert.deepEqual(whatIsInAName([{ "apple": 1, "bat": 2 }, { "apple": 1 }, { "apple": 1, "bat": 2, "cookie": 2 }], { "apple": 1, "cookie": 2 }), [{ "apple": 1, "bat": 2, "cookie": 2 }]);'
  - text: '<code>whatIsInAName([{ "apple": 1, "bat": 2 }, { "apple": 1 }, { "apple": 1, "bat": 2, "cookie": 2 }, { "bat":2 }], { "apple": 1, "bat": 2 })</code> should return <code>[{ "apple": 1, "bat": 2 }, { "apple": 1, "bat": 2, "cookie":2 }]</code>.'
    testString: 'assert.deepEqual(whatIsInAName([{ "apple": 1, "bat": 2 }, { "apple": 1 }, { "apple": 1, "bat": 2, "cookie": 2 }, {"bat":2}], { "apple": 1, "bat": 2 }), [{ "apple": 1, "bat": 2 }, { "apple": 1, "bat": 2, "cookie":2 }]);'
  - text: '<code>whatIsInAName([{"a": 1, "b": 2, "c": 3}], {"a": 1, "b": 9999, "c": 3})</code> should return <code>[]</code>'
    testString: 'assert.deepEqual(whatIsInAName([{ "a": 1, "b": 2, "c": 3 }], { "a": 1, "b": 9999, "c": 3 }), []);'

Solution

Offical soln:

function whatIsInAName(collection, source) {
  var arr = [];
  var keys = Object.keys(source);
  collection.forEach(function(e) {
    if(keys.every(function(key) {return e[key] === source[key];})) {
      arr.push(e);
    }
  });
  return arr;
}

My soln:

function whatIsInAName(collection, source) {
  // What's in a name?
  var arr = [];
  // Only change code below this line
  arr=collection.filter(function(obj){
  for(const prop in source){
    if(obj[prop]!==source[prop]){
      return false;
    }
  }
  return true;
});

  // Only change code above this line
  return arr;
}

whatIsInAName([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last: null }, { first: "Tybalt", last: "Capulet" }], { last: "Capulet" });

Other solns:
Using Object.keys(source) to get the keys and loop through the keys. Wherefore art thou - Hugh Winchester

let keys = Object.keys(source);
 for (var i = 0; i < keys.length; i++){

Wherefore art thou - freeCodeCamp using Modern JavaScript #4
Something cool about ES6 arrow functions: if we intend to return the whole body of a function we don't have to wrap it in curly braces - the return keyword is implicit.

const whatIsInAName = (collection, source) =>
  collection.filter(object =>
    Object.keys(source).every(key => object[key] === source[key]));

Useful Links

for...in
Array.prototype.every()
Object.prototype.hasOwnProperty()