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

Posted by Osama Awan
Osama Awan
Courses Plus Student 8,676 Points

Weird Error

var listItem = ['Apple', 'Banana', 'Mango', 'Orange']; var search;

while (true) { search = prompt("Search for a product, type 'list' to show all products and 'quit' to exit "); search = search.toLowerCase(); if (search === 'quit') { break; } else if (search === 'list') { document.write( listItem.join(', ')); } else { if ( listItem.indexOf(search) > -1) { document.write('<p>' + "Yes we have " + search + " in our product list " + '</p>'); } else { document.write('<p>' + "Sorry we don't have " + search + " in our product list " + '</p>'); } } }

getting this error in the Console Uncaught TypeError: Cannot read property 'toLowerCase' of null

1 Answer

Steven Parker
Steven Parker
229,744 Points
Steven Parker
Steven Parker
229,744 Points

To avoid this, check that "search" is not null (or not "falsey") before you perform the lower case conversion. (You may want to "break" if it is).

Additionally, to be able to match with your list of items, you will need to convert them also (or store them as lower case).

Osama Awan
Osama Awan
Courses Plus Student 8,676 Points

Thanks for your help, first alphabet of array elements were in upper case