function set_default_value_for_text_input_with_id(element_id, default_text) {
    element = document.getElementById(element_id);
    
    if (!element) return;
    
    if (element.type !='text') {
        return;
    }
    
    // Set / save the default text
    element.default_text = default_text;
    element.value = default_text;
    
    // Set the default color
    element.style.color = 'gray';
    
    element.onfocus =   function() { 
                            if (this.value == this.default_text) {
                                this.style.color = 'black';
                                this.value = '';
                            }
                        }
                        
    element.onblur =    function() {
                            if (this.value == '') {
                                this.style.color = 'gray';
                                this.value = this.default_text;
                            }
                        }
}

function initialize() {
    set_default_value_for_text_input_with_id('search_field', 'Search Here');
    set_default_value_for_text_input_with_id('email_signup_field', 'Enter email address here');
}