还有其他使用此.charAt（）的方式吗？

Question

I have a problem, when I used input[index] in the statement the reverse word didn't match the value of inputString. But this works in C#. When I try it in JavaScript is not working. I want to learn what are the other alternative way of .char() method. Can anybody solve my problem?

strReverse = "";
input = document.getElementById("inputValue").value;
i = input.length;

for(var j = i; j >= 0; j--) {
     strReverse = strReverse + input.charAt(j); // i used input[index]  
}

Answer 1

If you wish to use input[index] instead of input.charAt() then you need to address the issue that you are setting i = input.length;

So when you enter your loop for the first iteration, j will be equal to i . Meaning that you are trying to access the character at the index equal to the length of the string (when you do input[j] ). However, as arrays and string indexing starts at zero in javascript (and in most languages), there is no index at i (the length of the string), but, there is an index at i-1 , which will give the last character in the string. Thus, if you want to reverse your array using input[j] you need to start j in your for loop as j = i - 1 .

Take a look at the snippet for a working example:

 strReverse = ""; input = "level"; i = input.length; for(var j = i-1; j >= 0; j--) { strReverse = strReverse + input[j]; // i used input[index] } if(strReverse === input) { alert(input +" is a palindrome!") } else { alert(input +" is not a palindrome!"); }