JavaScript：为什么此代码不起作用？

Question

I am trying to create an text encrypter, but when i entered this code, nothing happens. What is wrong with my code?

function Encrypt(txt) {
var chars = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v','w', 'x', 'y', 'z'}
for (i = 0; i < txt.length; i++) {
    var chr = txt.charAt(i);
    var pos = chars.indexOf(chr);
    if (pos == chars.length) {
        pos = 0;
    }
    else {
        pos = pos++
    }
    txt.charAt(i) = chars[pos];
}
alert(txt);
}

Answer 1

You need

• array [] instead of object {} ,
• some declared variables
• an empty result string newText , a string is read only with the character access
• a valid check if the letter is not in the array
• increment pos without assignment.
• append the result string with the encoded character

 function Encrypt(txt) { var chars = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'], i, newText = '', chr, pos; for (i = 0; i < txt.length; i++) { chr = txt[i]; pos = chars.indexOf(chr); if (!~pos) { pos = 0; } else { pos++; } newText += chars[pos]; } document.write(newText); } Encrypt('test');

Answer 2

Because this is not an array, but object... and object has to have "index" : "value" structure.

Change this:

var chars = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v','w', 'x', 'y', 'z'}

to this:

var chars = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v','w', 'x', 'y', 'z']

Answer 3

Not considering the errors well described in the other answers, my proposal to encrypt a string is:

 function Encrypt(txt) { var chars = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v','w', 'x', 'y', 'z']; var txtResult = txt.split('').map(function(val) { var pos = chars.indexOf(val); return chars[(pos == chars.length) ? 0 : (pos + 1)]; }).join(''); document.write(txtResult); } Encrypt('gaemaf');