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JavaScript JavaScript Loops, Arrays and Objects Tracking Multiple Items with Arrays Useful Array Methods

Posted by Thomas Katalenas
Thomas Katalenas
11,033 Points

Bug

I found a bug, you type things that aren't on the list and prompt will return Yes, we have butter in the store.

butter is not in the list though....hmm

in python we'd do something like this.

for word in list: if word not in list: return False

var inStock = [ 'apples', 'eggs', 'milk', 'cookies', 'cheese', 'bread', 'lettuce', 'carrot', 'broccoli', 'pizza', 'potato', 'crackers', 'onion', 'tofu', 'frozen dinner', 'cucumber'];
var search;
var index;
var item;


function print(message) {
  document.write( '<p>' + message + '</p>');
}



while (true) {
  search = prompt("Search for a product in our store. Type 'list' to show all the produce and 'quit' to exit");

  if (search === 'quit'){
    break;
  }else if (search === 'list') {
    print(inStock.join(', '));
  }else {
    if ( inStock.indexOf(search)) {
      print( 'Yes, we have ' + search + ' in the store.');
    } else { 
      print( search + ' is not in stock.');
    }
  }
}

3 Answers

Thomas Katalenas
Thomas Katalenas
11,033 Points
Thomas Katalenas
Thomas Katalenas
11,033 Points

what is the difference between

if ( inStock.indexOf(search) != -1) and if ( inStock.indexOf(search) !== -1)

michael mead
michael mead
7,205 Points

!== is "strict equality operator". It compares value and type. Non-strict equality operators only compare value and would return true for "9" and 9 even though "9" is a string.

Daniel Perez Alvarez
Daniel Perez Alvarez
4,233 Points
Daniel Perez Alvarez
Daniel Perez Alvarez
4,233 Points

It seems that you forgot to check the return value of indexOf(search). That's why, no matter what item you enter, it would be always available in your store. Try adding this instead:

if ( inStock.indexOf(search) > -1 )  {
    print("Yes, we have " + search + " in our store.");
}
Daniel Perez Alvarez
Daniel Perez Alvarez
4,233 Points
Daniel Perez Alvarez
Daniel Perez Alvarez
4,233 Points

It seems that you forgot to check the return value of indexOf(search). That's why, no matter what item you enter, it would be always available in your store. Try adding this instead:

if ( inStock.indexOf(search) > -1 )  {
    print("Yes, we have " + search + " in our store.");
}