var searchMessage = "Search"; 			// string to prepopulate search input with
var searchInputSelector = ".main-search-fld";	// string CSS selector to target search input
var searchSubmitSelector = ".main-search-btn";	// string CSS selector to target search submit

$(document).ready(function () {
    							
	    prePopulateSearchField();
    	
	    // add onfocus event handler to search input
	    $(searchInputSelector).focus(function(e) {
		    clearSearchField();
	    });
    	
	    // add onblur event handler to search input
	    $(searchInputSelector).blur(function(e) { 
		    prePopulateSearchField();
	    });
    	
	    // add onkeypress event handler to search input
	    $(searchInputSelector).keypress(function(e) {
		    // if [enter] key
		    if(e.which == 13) {
			    // trigger click event on search button
			    $(searchSubmitSelector).click();
			    // alert("click: " + buttonId);				// for testing
			    // suppress default keypress behaviour
			    return false;
		    } else {
			    // enable default keypress behaviour
			    return true;
		    }
	    });
    	
	    // add onclick event handler to search button
	    $(searchSubmitSelector).click(function(e) {
		    submitSearchForm();
	    });
    	
    });

    function prePopulateSearchField() {
	    if ( $(searchInputSelector).val() == "" || $(searchInputSelector).val() == searchMessage ) {
		    $(searchInputSelector).val(searchMessage);
		    $(searchInputSelector).addClass("prePopulated"); 		// CSS class added to input so text is e.g. light grey instead of black
	    }
    }

    function clearSearchField() {
	    if ( $(searchInputSelector).val() == searchMessage ) {
		    $(searchInputSelector).val("");
		    $(searchInputSelector).removeClass("prePopulated");
	    }
    }

    function submitSearchForm() {
	    // do the necessary i.e. call the .net js postback function
	    // N.B. js postback function is often not present on initial page load
	    // so check this works before and after any other postbacks
	    // there is a trick to force it to be written to the initial page
	    // alert('submitSearchForm');						// for testing
    }