如何更改具有空替代文本的图像的替代文本

Question

I have a div inside whose chile tehre can be number of images What i want's to do is if there is any img with alt="" i want's to change it to alt="category" How can i do it with jquery. Currently ia m able to get all the img elements and trying to check there value first [so that if there is a alt have value i will not touch it] but unsuccessful My current code is

var label = $("#viewCategoriesForBlog").find('img').attr('alt');
for(var i=0;i<label.length;i++){
    alert( label[i].value);
}

Answer 1

var label = $("#viewCategoriesForBlog").find('img').attr('alt'); 
// label will hold only the first alt value

It has to be like

var label = $("#viewCategoriesForBlog").find('img');
for(var i=0;i<label.length;i++){
    alert( $(label[i]).attr('alt'));
}

Answer 2

此操作将解决您的最初问题：

 $('#viewCategoriesForBlog img[alt=""]').attr('alt', 'category');

Answer 3

Like this:

$("#viewCategoriesForBlog img[alt=''], #viewCategoriesForBlog img:not([alt])")
    .attr("alt", "Category");

Selectors explained:

• #viewCategoriesForBlog img[alt=""] returns img tags that have alt=""
• #viewCategoriesForBlog img:not([alt]) returns img tags that do not have alt attribute

Demo here

Answer 4

You need to loop over the elements in the selector. You cannot loop over attributes of the elements in a selector. Try this:

$("#viewCategoriesForBlog img").each(function(i, el) {
    alert($(el).prop('alt'));
});

Answer 5

try something like this

  $("#viewCategoriesForBlog").find('img').each(function(){
        if(this.alt.trim() == ''){
            this.alt = 'category';
        }
  })

Answer 6

This fiddle alerts all the empty alt tags: http://jsfiddle.net/4ZnJN/1/

$("img").each(function(){
        var label = $(this).attr('alt');            
        if(label.length < 1){
            alert(label);
        }
});

Might want to shrink it down to your specific structure in stead of all img tags

Answer 7

I'm aware that's absolutely not accessible, but here I only needed to avoid WCAG validator to highlight images with no alternative text.

var images = document.querySelectorAll('img');

if(images) {
    for (var i = images.length - 1; i >= 0; i--) {
        var alt = images[i].getAttribute('alt');
        if(!alt){
            images[i].setAttribute('alt', 'no alt text');
        }
    }
}