Question

I have this code working, but it seems clunky to me, is there a way to simplify? The gist of it is I’m checking the page width when the page loads and showing or hiding a div based on that (based on if the browser is wider or skinnier than 480 pixels). Then if the user resizes the browser window, I check the width again and show/hide the proper divs. Anyway this could be simplified with jquery or just js?

function pageWidth() {
        return window.innerWidth != null? window.innerWidth: document.body != null? document.body.clientWidth:null;
    }
    //Show/hide the correct div when the page loads
    if (pageWidth() >= 480) {
        $(".siteSearchDropdown").css("display", "none");
        $(".siteSearchSelect").css("display", "block");
    }
    if (pageWidth() < 480) {
        $(".siteSearchDropdown").css("display", "block");
        $(".siteSearchSelect").css("display", "none");
    }
    // Show/hide the correct dropdown when the browser window is resized
    $(window).resize(function() {
        if (pageWidth() >= 480) {
            $(".siteSearchDropdown").css("display", "none");
            $(".siteSearchSelect").css("display", "block");
        }
        if (pageWidth() < 480) {
            $(".siteSearchDropdown").css("display", "block");
            $(".siteSearchSelect").css("display", "none");
        }
    });

Answer 1

Rather than writing the code twice, write it once inside the window.resize event handler and then trigger a resize event on the window element:

$(window).resize(function() {
    if (pageWidth() >= 480) {
        $(".siteSearchDropdown").css("display", "none");
        $(".siteSearchSelect").css("display", "block");
    }
    if (pageWidth() < 480) {
        $(".siteSearchDropdown").css("display", "block");
        $(".siteSearchSelect").css("display", "none");
    }
}).trigger('resize');

Also, since this code will run many times when someone resizes their browser you should optimize your code by caching the selectors:

var $siteSearchDrioopdown = $(".siteSearchDropdown"),
    $siteSearchSelect     = $(".siteSearchSelect");
$(window).resize(function() {
    if (pageWidth() >= 480) {
        $siteSearchDrioopdown.css("display", "none");
        $siteSearchSelect.css("display", "block");
    }
    if (pageWidth() < 480) {
        $siteSearchDrioopdown.css("display", "block");
        $siteSearchSelect.css("display", "none");
    }
}).trigger('resize');

Note: I mentioned how resize event handler code is run many times when the browser is resized. To test this for yourself, just add this code to a page and watch your developer console fly:

$(window).resize(function (e) {
    console.log(e);
});

After looking at the code again you can optimize further by using an if/else statement rather than running the pageWidth() function twice:

var $siteSearchDrioopdown = $(".siteSearchDropdown"),
    $siteSearchSelect     = $(".siteSearchSelect");
$(window).resize(function() {
    if (pageWidth() >= 480) {
        $siteSearchDrioopdown.css("display", "none");
        $siteSearchSelect.css("display", "block");
    } else {//notice the change in structure so the `pageWidth()` function is only called once
        $siteSearchDrioopdown.css("display", "block");
        $siteSearchSelect.css("display", "none");
    }
}).trigger('resize');