CSS

convert string to uppercase while typing

// Using JS
function uppercase(obj){
    obj.value = obj.value.toUpperCase();
}

// Using CSS
id_name {
	text-transform: uppercase;
}

change text to uppercase while typing

$(function() {
  $('input[type=text]').keyup(function() {
    this.value = this.value.toLocaleUpperCase();
  });
});