cropper is not a function on is not a function

Question

I'm trying to make use of cropper plugin by fengyuanchen but meeting quite an impossible error

I constantly get into Uncaught TypeError: canvas.cropper is not a function even though I already tried everything I searched in your guide and even issues but I couldn't solve it. I try to initialize a cropper in canvas when my button is clicked, like this

$('#crop-mode').click(function(e){
                    var canvas=$('#image-display canvas')[0];
                    var options={
                        viewMode:0,
                        dragMode:'crop',
                        aspectRatio: NaN,
                        preview:'.extra-preview',
                        responsive:true,
                        cropBoxMovable: true,
                        cropBoxResizable: true,
                        autoCropArea:0.8
                    };
                    canvas.cropper(options);
                    canvas.on({
                        'build.cropper': function (e) {
                            console.log(e.type);
                        },
                        'built.cropper': function (e) {
                            console.log(e.type);
                        },
                        'cropstart.cropper': function (e) {
                            console.log(e.type, e.action);
                        },
                        'cropmove.cropper': function (e) {
                            console.log(e.type, e.action);
                        },
                        'cropend.cropper': function (e) {
                            console.log(e.type, e.action);
                        },
                        'crop.cropper': function (e) {
                            console.log(e.type, e.x, e.y, e.width, e.height, e.rotate, e.scaleX, e.scaleY);
                        },
                        'zoom.cropper': function (e) {
                            console.log(e.type, e.ratio);
                        }
                    });
                });

I'm completely in vain

There is also another error: canvas.on is not a function

I don't know why. I already include jQuery 3.1

Answer 1

From the jQuery docs:

Attach an event handler function for one or more events to the selected elements.

Now, canvas after var canvas=$('#image-display canvas')[0]; is not a selected element. It's the first property of the selected element. $() will return a selected element (if found, obviously), but $()[0] is something completely else. Drop the [0].

Answer 2

First, make sure you have the library loaded with jquery:

<script src="/path/to/jquery.js"></script>
<script src="/path/to/cropper.js"></script>

Cropper is a jquery extension, thus instead of:

var canvas=$('#image-display canvas')[0];

do:

var canvas=$('#image-display canvas');