---
title: Wherefore Art Thou
---
 Remember to use **`Read-Search-Ask`** if you get stuck. Try to pair program  and write your own code 
###  Problem Explanation:
Write an algorithm that will take an `array` for the first argument and return an `array` with all the `object`s that matches all the properties and values in the `Object` passed as second parameter.
#### Relevant Links
* For Loops
* Array.prototype.filter()
* Object.hasOwnProperty()
Object.keys()
##  Hint: 1
You may use `for` loop or the `Array.prototype.filter` method.
> _try to solve the problem now_
##  Hint: 2
Try to use the `Object.prototype.hasOwnProperty` method to know if the property name exists in an object (as its own property).
> _try to solve the problem now_
##  Hint: 3
Check equivalence of `Object` in `collection` with `Object` passed as second parameter to `whatIsInAName` function.
> _try to solve the problem now_
## Spoiler Alert!
**Solution ahead!**
##  Basic Code Solution:
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
### Code Explanation:
* 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`;
#### Relevant Links
* For Loops
* Array.prototype.filter()
* Object.hasOwnProperty()
##  Intermediate Code Solution:
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
### Code Explanation:
* 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.
#### Relevant Links
* Array.prototype.filter()
* Array.prototype.every()
* Object.hasOwnProperty()
##  Advanced Code Solution:
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
.map(function(key) {
return obj.hasOwnProperty(key) && obj[key] === source[key];
})
.reduce(function(a, b) {
return a && b;
});
});
}
// test here
whatIsInAName([{ first: "Romeo", last: "Montague" }, { first: "Mercutio", last: null }, { first: "Tybalt", last: "Capulet" }], { last: "Capulet" });
 Run Code
### Code Explanation:
* We start by filtering through `collection` using `Array.filter()`.
* Next, we map through all keys and return Boolean values based on the check conditions: both the key and its corresponding value must exist within the object we are filtering through.
* Then we reduce the mapped Boolean values to a single Boolean that indicates whether all srcKeys pass the conditions checked above.
* This single Boolean will be used to filter through the collection.
#### Relevant Links
* Array.prototype.filter()
* Array.prototype.reduce()
* Object.hasOwnProperty()
##  NOTES FOR CONTRIBUTIONS:
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* Add an explanation of your solution.
* Categorize the solution in one of the following categories — **Basic**, **Intermediate** and **Advanced**. 
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> See  **`Wiki Challenge Solution Template`** for reference.