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Write an algorithm that will take an array for the first argument and return an array with all the objects that matches all the properties and values in the Object passed as second parameter.

• For Loops
• Array.prototype.filter()
• Object.hasOwnProperty()

You may use for loop or the Array.prototype.filter method.

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Try to use the Object.prototype.hasOwnProperty method to know if the property name exists in an object (as its own property).

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Check equivalence of Object in collection with Object passed as second parameter to whatIsInAName function.

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Solution ahead!

function whatIsInAName(collection, source) {
  // "What's in a name? that which we call a rose
  // By any other name would smell as sweet.”
  // -- by William Shakespeare, Romeo and Juliet
  var srcKeys = Object.keys(source);

  // filter the collection
  return collection.filter(function (obj) {
    for(var i = 0; i < srcKeys.length; i++) {
      if(!obj.hasOwnProperty(srcKeys[i]) || obj[srcKeys[i]] !== source[srcKeys[i]]) {
        return false;
      }
    }
    return true;
  });
}

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

🚀 Run Code

• We filter through the array using .filter().
• Using a for loop we loop through each item in the object.
• We use a if statement to check if the object in the collection doesn't have the key and the property value doesn't match the value in source.
• We return false if the above if statement is correct. Otherwise, we return true;

• For Loops
• Array.prototype.filter()
• Object.hasOwnProperty()

function whatIsInAName(collection, source) {
  // "What's in a name? that which we call a rose
  // By any other name would smell as sweet.”
  // -- by William Shakespeare, Romeo and Juliet
  var srcKeys = Object.keys(source);

  return collection.filter(function (obj) {
    return srcKeys.every(function (key) {
      return obj.hasOwnProperty(key) && obj[key] === source[key];
    });
  });
}

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

🚀 Run Code

• We filter through the collection using .filter().
• Next, we return a Boolean value for the .filter() method.
• Finally, we reduce to Boolean value to be returned for the .every() method.

• Array.prototype.filter()
• Array.prototype.every()
• Object.hasOwnProperty()

function whatIsInAName(collection, source) {
  // "What's in a name? that which we call a rose
  // By any other name would smell as sweet.”
  // -- by William Shakespeare, Romeo and Juliet
  var srcKeys = Object.keys(source);

  // filter the collection
  return collection.filter(function (obj) {
    return srcKeys.reduce(function (res, key) {
      return obj.hasOwnProperty(key) && obj[key] === source[key];
    }, false);
  });
}

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

🚀 Run Code

• We start by filtering through collection using Array.filter().
• Next, we return a Boolean value for the filter callback using .reduce().
• We reduce to Boolean value to be returned by .reduce().

• Array.prototype.filter()
• Array.prototype.reduce()
• Object.hasOwnProperty()

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Thanks @abhisekp @dting @coded9 for your help with Algorithm: Wherefore Art Thou

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