Enforce ALT text for Image on a Sharepoint Page

I had a requirement to enforce the ALT text for an image while user put any image on content editor web part on a sharepoint page.

For this purpose I need to inject the Javascript while user trying to save or checkin the page.

While you try to enforce the Alt Text for your image then you will get lot of sharepoint images. So it’s difficult to identify your image between them. I tried a lot for that finally I created the array for the sharepoint OOB images and skip those images to get my image which I added on content editor web part.

Here is the script

Paste this code on your Master page if you would like to have this functionality on every SharePoint page. 

Or else you can paste this script on any specific layout page if would like to have this functionality for any 

specific Page layout page.

var customJS = WebForm_OnSubmit;
WebForm_OnSubmit = function () {
  isValid = checkAltTextForImage(); 
  if (isValid) return customJS.apply(this, arguments);
  else {
    $('span[id*=notification_]').remove(); //removes the default save notification 
    return false;
  }
}
      

function checkAltTextForImage() {
    var flag = true;
    if ($('.ms-promotedActionButton')[2].text == "Save") {
        if ($('img[alt=""]').length > 0) {
            var image = new Array();
            image[0] = "formatmap32x32.png?rev=23";
            image[1] = "publishing.png?rev=23";
            image[2] = "formatmap16x16.png?rev=23";
            image[3] = "analyticsreport32x32.png?rev=23";
            image[4] = "SocialTagsAndNotes_32.png?rev=23";
            image[5] = "blank.gif?rev=23";
            image[6] = "crperspc.gif";
            
            for (var i = 0; i < $('img[alt=""]').length; i++) {
                if (isExist(image, $('img[alt=""]')[i].nameProp) == -1)
                {
                    var imageName = $('img[alt=""]')[i].nameProp;
                    alert("There is no alternate text defined for Image " + imageName + ". Please provide the Alternate Text");
                    flag = false;
                    break;
                }
            }
        }
    }
    $('.ms-cui-tb').focus();
    return flag;
}

function isExist(obj, str) {
    var returnItem = 0;
    var arr = obj.toString().split(',');
    if (str.indexOf('?') > -1) {
        returnItem = 1;
    }
    else {
        for (var i = 0; i < arr.length; i++) {
            if (arr[i] === str) {
                returnItem = i;
                break;
            } else {
                returnItem = -1;
            }
        }
    }
    return returnItem;
}