#JuxtaposeJS

JuxtaposeJS is a simple, open source tool for creating before/after image sliders. Just provide two image URLs and Juxtapose will do the rest of the work for you. Below are instructions for implementing Juxtapose with HTML and Javascript but we also have a tool that lets you make a slider without needing to know any code.

If you want to contribute to Juxtapose, check out the DEVELOPERS.md file for installation instructions. Fork the project, create a new branch with your features, and submit a pull request. Thanks for your help!

###Instructions

####HTML Implementation The easiest way to implement the image slider is to add this code to your markup:

<div class="juxtapose">
    <img src="http://example.com/firstimage.jpg" />
    <img src="http://example.com/secondimage.jpg" />
</div>
<script src="http://cdn.knightlab.com/libs/juxtapose/latest/js/juxtapose.min.js"></script>

Each image can also take some additional attributes.

<img src="http://image.jpg" data-label="2009" data-credit="Alex Duner/Northwestern Knight Lab" />

If each image has an data-label attribute defined, the slider will display a label on each image. If each image has a data-credit attribute defined, the slider will display a credit for each image.

The main wrapper can also take some additional attributes as well to specify a few options:

<div id="juxtapose-wrapper" class="juxtapose" data-startingposition="35%" data-showlabels="false" data-showcredits="false" data-animate="false">

Specifying a starting position with data-startingposition lets you focus the users attention on the part of the image where the change is most noticeable. To toggle the visibility of the labels and the credits respectively, set data-showlabels and data-showcredits to false. And to disable the animation, set data-animate to false.

If you are using Juxtapose in an existing responsive iFrame solution like pym.js and don't want to use Juxtapose's built in (but faily opinionated) responsive iFrame solution, you can set data-makeresponsive to false.

####Javascript Implementation The JXSlider class takes three arguments. First, is the string of the ID of the element you want to turn into a slider. Second is an array of two objects. Each object must have src defined and can optionally define a label and a credit. The third argument lets you set additional options for the image slider.

<div id="foo"></div>
<script>
slider = new juxtapose.JXSlider('#foo',
    [
        {
            src: 'http://firstimage.jpg',
            label: '2009',
            credit: 'Image Credit'
        },
        {
            src: 'http://secondimage.jpg',
            label: '2014',
            credit: "Image Credit"
        }
    ],
    {
        animate: true,
        showLabels: true,
        showCredits: true,
        startingPosition: "50%"
    });
</script>

###Modifications ####CSS You can customize how JuxtaposeJS looks by modifying its CSS. For instructions, click here.

####JavaScript

The JXSlider class contains a few methods you can use to modify your sliders.

If you instantiated your sliders with the HTML method but still want to access one of your sliders programmatically, JuxtaposeJS creates an array of the JXSliders on your page that you can access with juxtapose.sliders.

JXSlider.updateSlider(percentage, animate)

Percentage indicates where you want to set the handle relative to the left side of the slider. If you set animate to true, the handle will animate to the new location; if animate is set to false, the handle will not.