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JavaScript JavaScript Foundations Arrays Methods: Part 2

Jake Adam
Jake Adam
9,226 Points
Posted by Jake Adam
Jake Adam
9,226 Points

Help with JS code challenge

How do I sort this: var saying2 = ["The", "quick", "brown", "fox", "jumped", "over", "the", "lazy", "dog's", "back"]; by the length of the strings from shortest to largest? It wasn't in the video and I don't know where to start.

2 Answers

Alex Robertson-Brown
PLUS
Alex Robertson-Brown
Courses Plus Student 8,956 Points
Alex Robertson-Brown
Alex Robertson-Brown
Courses Plus Student 8,956 Points

Yeah this one caught me out as well. The answer is a slight modification to one of the examples in the video:

var saying2 = ["The", "quick", "brown", "fox", "jumped", "over", "the", "lazy", "dog's", "back"];

saying2.sort(function(a,b){
  return a.length >= b.length;
})

Hope This helps.

Jake Adam
Jake Adam
9,226 Points
Jake Adam
Jake Adam
9,226 Points

Thank you it does.

Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

Hi Alex,

You should always return a positive, negative, or zero value from the compare function. You will get yourself into trouble with returning a boolean value. It may pass this challenge for this very specific array but it's not correct to do this and it will not always work.

For this to work it relies on the sort method being stable. Not all of the browsers implement a stable sort.

One experiment that you can do is run your code above as is in the chrome console and I think you'll find that it does sort correctly although it does not maintain original order of equal length strings.

Then try this code:

var saying2 = ["The", "quick", "brown", "fox", "jumped", "over", "the", "lazy", "dog's", "back", "this_makes_11"];

saying2.sort(function(a,b){
  return a.length >= b.length;
})

Here I've added one more element to make 11 total. It does not sort this correctly. This is because chrome implements a stable sort for 10 elements or less and switches to a unstable sort beyond 10 elements.

The sort method is expecting a positive, negative, or zero value to be returned so you don't want to be returning true or false.

Jason Anello
PLUS
Jason Anello
Courses Plus Student 94,610 Points
Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

Hi Jake,

The example given in the previous video was to sort numbers.

my_array.sort(function(a, b) {
  return a - b;
});

By subtracting the 2 numbers that are passed in you'll be returning either a positive, negative, or zero value which tells the sort method the order of those 2 items. I believe Jim talks about this in the video. You can also read more about the compare function here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort

In this code challenge you want to sort by string length. So two strings from the array will be passed in for a and b and you would want to subtract their lengths.

saying2.sort(function(a, b) {
  return a.length - b.length;
});
Jake Adam
Jake Adam
9,226 Points
Jake Adam
Jake Adam
9,226 Points

That link really helped me understand the sort function thank you for your help!