How to change default html for adding image in Tinymce

Question

When i add an image in tinymce, this is the default html source code i get:

<p><img class="img-responsive img-post" src="/Images/uploads/img.png" alt="" /></p>

How do i change this? to something like:

<p><img class="img-responsive img-post" data-original="/Images/uploads/img.png" src="/Images/loading.gif" alt="" /></p>

Where i have data-original as the src and src is the loading icon, it needs to be like this because i have lazy loading on images.

I know you can extend valid elements using:

extend_valid_elements: "data-original"

but how do i change the structure of default html source code? Is there something like on selecting ok for image insert callback??

Update:

Here is my tinymce initiation code:

/******************************tinyMce*******************************/
function tinyMce() {
    tinymce.init({
        theme: "modern",
        selector: "#mceEditor",
        height: 500,
        extend_valid_elements: "data-original",
        relative_urls: true,
        convert_urls: false,
        image_advtab: true,
        image_title: false,
        image_description: false,
        image_dimensions: false,
        image_class_list: [
            { title: "Responsive", value: "lazy img-responsive img-post" }
        ],
        image_list: function (success) {
            $.ajax({
                url: "/Image/List",
                type: "GET",
                dataType: "json",
                success: function (data) {
                    success(data);
                }
            });
        },
        // enable automatic uploads of images represented by blob or data URIs
        automatic_uploads: true,
        // URL of our upload handler (for more details check: https://www.tinymce.com/docs/configure/file-image-upload/#images_upload_url)
        images_upload_url: "/Image/Upload",
        // here we add custom filepicker only to Image dialog
        file_picker_types: "image",
        // and here's our custom image picker
        file_picker_callback: function (cb, value, meta) {
            var input = document.createElement("input");
            input.setAttribute("type", "file");
            input.setAttribute("accept", "image/*");

            // Note: In modern browsers input[type="file"] is functional without 
            // even adding it to the DOM, but that might not be the case in some older
            // or quirky browsers like IE, so you might want to add it to the DOM
            // just in case, and visually hide it. And do not forget do remove it
            // once you do not need it anymore.

            input.onchange = function () {
                var file = this.files[0];

                var reader = new FileReader();
                reader.readAsDataURL(file);
                reader.onload = function () {
                    // Note: Now we need to register the blob in TinyMCEs image blob
                    // registry. In the next release this part hopefully won't be
                    // necessary, as we are looking to handle it internally.
                    var id = "blobid" + (new Date()).getTime();
                    var blobCache = tinymce.activeEditor.editorUpload.blobCache;
                    var base64 = reader.result.split(',')[1];
                    var blobInfo = blobCache.create(id, file, base64);
                    blobCache.add(blobInfo);

                    // call the callback and populate the Title field with the file name
                    cb(blobInfo.blobUri(), { title: file.name });
                };
            };

            input.click();
        }
    });
}

I am thinking about another way now, if i can replace default src attribute inside tinymce to data-original, that would be perfect, but inside tinymce, if i use data-original, it won't show the picture, it justs shows blank. Is there a way to tell tinymce when adding an image, put data-original instead of src and read from data-original instead of src?

so from this:

<p><img class="img-responsive img-post" src="/Images/uploads/img.png" alt="" /></p>

to this without src at all:

<p><img class="img-responsive img-post" data-original="/Images/uploads/img.png" alt="" /></p>

Answer 1

Here is a way to detect when an image gets inserted into the editor.

JS

var newSrc = "/Images/loading.gif";


tinymce.init({
  selector: 'textarea',
  plugins: "image",
  toolbar: "image",
  height: 350,
    setup: function(editor){
    editor.on('NodeChange', function (e) {
      if(e.element.tagName === "IMG"){          
        e.element.setAttribute("data-original", e.element.currentSrc);
        e.element.setAttribute("src", newSrc);
      }
    });
  }
});

You can access the element by listening to the NodeChange event. Then checking tagName is of type IMG. Then we just set our attributes normally.

Check this Demo

Answer 2

...but inside tinymce, if i use data-original, it won't show the picture, it just shows blank.

Keep doing what you are doing here and simply add a change handler to add new src...

editor.on('Change', function (e) {
    // Get images that have data-original attribute but not src
    $( 'img[data-original]' ).not( 'img[src]' )
      .attr( 'src', '/Images/loading.gif' ) // Add src
} );

Answer 3

You can solve this problem with regular expression and string replace method the function will return the replacement for the match.. like the example below

// tinymce returning string
let content = '<p><img class="img-responsive img-post" src="/Images/uploads/img.png" alt="" /></p><p><img class="img-responsive img-post" src="/Images/uploads/img2.png" alt="" /></p>';

// searching through all the img tags in the content..
content = content.replace(/<img(\s+[^>]*)src="([^"]*)"([^>]*)>/g,function(full,key, value){
 return `<img ${key} src="/Images/loading.gif" data-original="${value}" alt="">`;
});


//content replaced
console.log(content);

A regular expression is used to match all the img tags, then we just the new data-original attribute and replace it in the original string