Javascript 阵列反向 function 不起作用

Question

I have a question with my homework

var NumberOfString = new Array(5);
NumberOfString = prompt("정수 5개를 입력하세요: ");
document.write("입력된 수의 배열" + "<br/>" + NumberOfString + "<hr>");
document.write("역순으로 재정렬된 배열" + "<br>");
document.write(NumberOfString.reverse());

This is my code. The function array.reverse doesn't work. I want to know why? Thanks!

Answer 1

You can reverse string with NumberOfString.split('').reverse().join('') .

Note

When you write NumberOfString = prompt("정수 5개를 입력하세요: "); it will convert your NumberOfString array to string as prompt returns the string .

String do not have reverse method. But you can use split('') to convert it to array then perform reverse and join it to get reverse string.

 var NumberOfString = new Array(5); NumberOfString = prompt("정수 5개를 입력하세요: "); document.write("입력된 수의 배열" + "<br/>" + NumberOfString + "<hr>"); document.write("역순으로 재정렬된 배열" + "<br>"); document.write(NumberOfString.split('').reverse().join(''));

Answer 2

because the type of NumberOfString is string. You can try this:

var NumberOfString = new Array(5);
var anySymbol = ''; 
NumberOfString = prompt("정수 5개를 입력하세요: ");
document.write("입력된 수의 배열" + "<br/>" + NumberOfString + "<hr>");
document.write("역순으로 재정렬된 배열" + "<br>");
document.write(NumberOfString.split(anySymbol).reverse());

Answer 3

The problem is at the last line.

reverse() method works with arrays

so you have to convert your string to an array by split() method.

and then set it back to a string by using join() method

 var NumberOfString = new Array(5); NumberOfString = prompt("정수 5개를 입력하세요: "); document.write("입력된 수의 배열" + "<br/>" + NumberOfString + "<hr>"); document.write("역순으로 재정렬된 배열" + "<br>"); // here you have to convert the string to an array by split('') // then use reverse method therfore set it back to a string by join('') document.write(NumberOfString.split('').reverse().join(''));