Bывести без повторов:

[Sweet]

array.filter( function ( item, index, array ){
  return array.indexOf( item ) == index;
} );

[JsLoveR]

//Способ 1
	var arr = ["apple", "orange", "cherry", "banana", "apple", "cherry"];
	var flag = [], clear = [] , i = arr.length;
	while (i--) {
		var str = arr[i];
		if (flag[str] != str) {
			clear.push(str);
		}
		flag[str] = str;
	}
	alert(clear.join(", "));
	
	//Способ 2
	for(var i = 0; i < arr.length; i++) {
		for(var j = i + 1; j < arr.length; j++) {
			if(arr[i] == arr[j]) {
				arr.splice(i, 1)
			}
		}
	}
	alert(arr.join(", "));