[解決済み] 配列から先頭の要素を取り除き，配列から先頭の要素を除いた値を返します．

var myarray = ["item 1", "item 2", "item 3", "item 4"];

//removes the first element of the array, and returns that element.
alert(myarray.shift());
//alerts "item 1"

//removes the last element of the array, and returns that element.
alert(myarray.pop());
//alerts "item 4"

var myarray = ["item 1", "item 2", "item 3", "item 4"];
    
myarray.shift();
alert(myarray);

var myarray = ["item 1", "item 2", "item 3", "item 4"];
  
alert(myarray.slice(1));