loop

gistfile1.js

var foo = [
        { "id": 1, "alt": "Orange" },
        { "id": 2, "alt": "Apple" },
        { "id": 3, "alt": "Banana" }
    ],
    item,
    html;

for ( var i = 0, len = foo.length; i < len ; i++ ) {
	item = foo[i];

	if ( i % 5 === 0 && i !== 0 ) {
		html += '</div></li>' + "\n";
	}
	if ( i % 5 === 0 ) {
		html += '<li><div>' + "\n";
	}
	html += '<div class="box"><img src="item'+ item.id +'.png" alt="'+ item.alt +'" /></div>' + "\n";
}
html += '</div></li>' + "\n";