Try this - you can change the wait for even a longer time by changing the 1000 to a bigger number.
var myArray1 = ['category1','category2'];
for (var i = 0; i < myArray1.length; i++) {
setTimeout("addCategory('" + myArray1[i] + "')", 1 * 1000);
}
function addCategory(categoryName){
$("#txt1").val(categoryName);
$("#btn1").click();
}