Question

I need to create one button that will cycle through 3 states. For some reason that is incredible challenging to find. The functions in each state are simple style changes, example:

click 1: hide div
click 2: show hidden div, change bg-color
click 3: reset bg-color, change font
click 1: reset font, hide div

Any ideas? I can’t use jquery (class assignment, not allowed)

Answer 1

Cou could use an array, with a function for each state change, and a counter variable which cycles through the possible states.

Then simply invoke the current state function through an click handler of the button.

Something like this could do it

var toggle = (function (el) {
    var div = document.getElementById(el); //Get the div you want to change
    var states = []; //The Array to hold the functions
    var style = {} //Will be used to save the current style
    for (var att in div.style) //Saves the style of the div *I was just lazy and did a for loop*
    style[att] = div.style[att]

    var current = 0; //The Counter

    states[0] = function () { //The first state function
        div.style["font-family"] = style["font-family"]
        div.style.display = "none";
    };
    states[1] = function () {
        div.style.display = "block";
        div.style["background-color"] = "rgb(" + [rand(), rand(), rand()] + ")"; // [1,2,3] toString is "1,2,3"
    };
    states[2] = function () {
        div.style["background-color"] = style["background-color"];
        div.style["font-family"] = "Courier New";
    }

    function rand() { //ONly to return a random number for a random bgcolor
        return ~~(Math.random() * 255)
    }
    return function () {  //The function which cycles through the states
        states[current]() //Invokes the current statechange function
        current = (current + 1) % (states.length); //Increments the counter and uses modulo to cycle
    }
})("div");

document.getElementById("click")
    .addEventListener("click", toggle);

Heres an example on JSFiddle

Update:

I modified it a bit and commented the changed code, this should be able of changing the states of multiple elements on a page

    function rand() {
        return~~ (Math.random() * 255);
    }


    var makeToggle = function (states, elements) { // I Changed it to makeToggle, The first argument accepts an array of states to cycle through, the second either an array of elements, or an array of objects with the element property (and an optional state function)
        var current = 0; //Sets the counter to zero

        for (var i = 0, ilen = elements.length; i < ilen; i++) {
            if (!elements[i].element) { //check if you passed an Object with the `element` Property
                elements[i] = {
                    element: elements[i] //If it was an array, the arrays element will be set to an object
                }; //to support arrays only
            }
            elements[i].style = {}; //to save the original style in the object
            for (var att in elements[i].element.style) {
                elements[i].style[att] = div.style[att]; // saves it
            }
        }

        function doForElements() { //Invokes either the state function passed with an element, or the general statefunction
            for (var i = 0, ilen = elements.length; i < ilen; i++) {
                var state = elements[i].states;
                if (state && typeof state[current] === "function") state = state[current];
                else state = states[current];
                state(elements[i].element, elements[i].style); //Invokes the function with the element as first parameter and the original style as second
            }

        }
        return function () { //Returns the function for the click handler
            doForElements();
            current = (current + 1) % (states.length); //cycles the current state counter
        };
    };

    var states = []; //Here the General State change functions get defined
    states[0] = function (div, style) {
        div.style["font-family"] = style["font-family"];
        div.style.display = "none";
    };
    states[1] = function (div, style) {
        div.style.display = "block";
        div.style["background-color"] = "rgb(" + [rand(), rand(), rand()] + ")";
    };
    states[2] = function (div, style) {
        div.style["background-color"] = style["background-color"];
        div.style["font-family"] = "Courier New";
    };


    var elements = [].slice.call(document.getElementsByTagName("div")); //To actually get an Array of the NodeList (all divs on the page)

    elements[4] = { //changes the 5th element (which should receive a special statechange function)
        element: elements[4],
        states: {
            1: function (div, style) { //Use an Objects property to pass an single state change instead of an array with functions
                div.style.display = "block";
                div.style["background-color"] = "yellow";
            }
        }
    };


    var toggle = makeToggle(states, elements); //sets the function for the click handler to toggle
    //Pass an Object with the Elements and an optional st

    document.getElementById("click")
        .addEventListener("click", toggle); //binds the function

Heres a JSBin to try it out