Checking a list of Strings(Array) as palindrome in JS

Question

Please solve my issue, I am going to check a list of strings as palindrome, if any of the string from the array is palindrome then it should display a result true, the result should be in string value not in Boolean value. I had tried so many times but it is not displaying the result; See my code below:-

function checkPry()
{
    var status = new Array();
    var wordList1 = document.getElementById("tk").value;
    var wordArray = new Array();
    wordArray = wordList1.split(" "); 
    var alength = wordArray.length; 
    for(var i=0; i <= alength; i++)
    {
        var str = wordArray[i];
        var chrlength = str.length;
        var lw = chrlength - 1;
        var chk = "";
        for(j=0; j<=chrlength; j++)
        {
            if(str.charAt(j) != str.charAt((lw - j)))
            {
                chk = "false";
                break;
            }
            else
            {
                chk = "true";
            }
        }
        if (chk == "true")
        {
            status[i] = "true";
        }
        else if (chk == "false")
        {
            status[i] = "false"
        }
    }
    var displayStr = status.toString();
    document.getElementById("show").innerHTML = displayStr;
}

like If I am giving the input value as [dalad radar jaijai rexem] then it should be give result as [true,true,false,false], Please help me in that; you can also check the fiddle below:--

http://jsfiddle.net/yePQ4/1/

Thanks!

scrblnrd3 · Accepted Answer · 2013-12-18T15:58:57.533

5

You just need to check if something reversed is the same

function reverse(s){
     return s.split("").reverse().join("");
}

function checkIsPalindrome(arr){
   var result=[];
   for(var i=0;i<arr.length;i++){
       result.push(arr[i]==reverse(arr[i]));
   }
   return result;
}

edited Dec 18 '13 at 15:58

answered Dec 18 '13 at 15:52

scrblnrd3

7,228
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can you provide a fiddle for that, it's hard to understand – N.P. SINGH Dec 18 '13 at 16:02
http://jsfiddle.net/8pLFC/ – scrblnrd3 Dec 18 '13 at 16:06
thank you so much... it's very optimized code – N.P. SINGH Dec 18 '13 at 17:45
well the code is really good, but the issue is I am just beginner, and it's hard to understand it. can you provide me some instructions on my code, that where is the issue, why my logic is not working, see my code please. it will be a great help for me. – N.P. SINGH Dec 18 '13 at 17:56
Performance isn't as good as it is here http://stackoverflow.com/questions/22111507/how-to-write-palindrome – nanobash Mar 05 '14 at 16:34

Dagg Nabbit · Answer 2 · 2013-12-18T16:08:15.020

2

Just for fun, here's an alternate version of @scrblnrd3's answer that uses a regex to reverse the string instead of split/join.

function reverse(text) {
    return text.replace(/./g, function(c, i, s) { return s[s.length - 1 - i]; });
}

function checkIsPalindrome(arr) {
    var result = [];
    for (var i = 0; i < arr.length; i++) {
        result.push(arr[i] == reverse(arr[i]));
    }
    return result;
}

edited Dec 18 '13 at 16:08

answered Dec 18 '13 at 16:02

Dagg Nabbit

75,346
19
113
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can you create a fiddle so I can understand how's it will be use, I am just a beginner in JS – N.P. SINGH Dec 18 '13 at 16:06
2

http://jsfiddle.net/8pLFC/1/ :p Please dont accept this answer though, scrblnrd3 deserves credit for it. – Dagg Nabbit Dec 18 '13 at 16:09

Checking a list of Strings(Array) as palindrome in JS

2 Answers2