how to make input field case insensitive?

[juanfra]

i have made an array and i am going to find out the record, when i am going to find the record in upper case words than it is ok but when i am going to find the records with lower case letters than it is not finding the records. folloying is the script i have made.\[code\]if (document.getElementById('drop_down_list_1').value =http://stackoverflow.com/questions/15864077/="Genetic") { if (document.getElementById('search_input').value =http://stackoverflow.com/questions/15864077/="") { alert("Please Enter a charactor / word.."); } else { var con = document.getElementById('first_div'); var con2 = document.getElementById('first_div2'); var char = document.getElementById('search_input').value; var str = ''; var j = 0; var ad = ['GLARIFIDE Deadlines 2012 - 2013 Nov', 'REPRODUCTIVE VACCINES