SO - 15001443

JavaScript

var $img = $('div#header img').first();
var flag = false;
setInterval(function(){
    console.log('image' + (flag ? 1 : 2) + '.jpeg')
    $img.attr('src', 'image' + (flag ? 1 : 2) + '.jpeg' );
    flag = !flag;
}, 1000);