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

Peter May
Peter May
16,376 Points
Posted by Peter May
Peter May
16,376 Points

Why does the if statement "instock.indexOf(search) < -1" not work unless I change it to ">=0".

I couldn't get the search function to find stuff until I changed the if statement from ">-1" to ">=0". why doesn't it wrok with "-1"?

if(inStock.indexOf( search ) >=0 ){ print('yes we have '+ search+ ' in our stock.</p>'); } else{ print(search + ' is not in stock.');

Here is a link to my code.

https://w.trhou.se/dawof2rx73

2 Answers

Steven Parker
Steven Parker
229,644 Points
Steven Parker
Steven Parker
229,644 Points

You've mentioned a few different comparison operations, only one would work.

  • if your test is " > -1", it should work
  • but " >= -1" would not work because it accepts the not-found condition (-1)
  • also " < -1" would not work because it is looking for other negative values
<noob />
<noob />
17,062 Points
<noob />
<noob />
17,062 Points

indexOf returns -1 if the element is not exists in the array. if the evultion of the expression returns a number above -1 it means that the element is inside the array- it give u back the index.