Using mod to wrap around

There might be a more elegant way around this, but this is simple:

$(".previous").click(function(){
    if (--index < 0) index = arrayLength - 1;
    $('.catalog-img-container').attr("src", javascript_array[index%arrayLength]);
}); 

Since --index%arrayLength doesn't work, just add the length of the array prior to taking the modulo:

index = (index+arrayLength-1) % arrayLength

You could also do

(index+=arrayLength-1)%arrayLength

but this will lead to index getting very large, possibly out of range over enough time.

You can also use a handy object for it.

var Cursor = function (array) {
  var idx = 0;
  this.prev = function () {
    idx = (!!idx ? idx : array.length) - 1;
    return array[idx];
  };
  this.current = function () {
    return array[idx];
  };
  this.next = function () {
    idx = (idx + 1) % array.length;
    return array[idx];
  };
  return this;
};

For example,

var $container = $(".catalog-img-container");
var cursor = new Cursor(javascript_array);

$container.attr("src", cursor.current());

$(".next").click(function(){
  $container.attr("src", cursor.next());
});         

$(".previous").click(function(){
  $container.attr("src", cursor.prev());
});