Is Palindrome?

JavaScript performance comparison

Revision 3 of this test case created


a silly test of palindrome testing techniques

Preparation code

  function f1(str) {
    return str === str.split('').reverse().join('');

  function f2(str) {
    var i = str.length - 1;
    var k = 0;
    while (i > k) {
      if (str.charAt(k++) !== str.charAt(i--)) return false;
    return true;

  function f3(str) {
    return str.substring(0, Math.floor(str.length / 2)) == (str.substring(Math.ceil(str.length / 2)).split('').reverse().join(''));
Benchmark.prototype.setup = function() {
    var str1 = "abcdefghijklmnopqrstuvwxyzzyxwvutsrqponmlkjihgfedcba";
    var str2 = "abcdefghijklmnopqrstuvwxyzyxwvutsrqponmlkjihgfedcba";
    var str3 = "abcdefghijklmnopqrstuvwxyzZyxwvutsrqponmlkjihgfedcba";

Test runner

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Testing in unknown unknown
Test Ops/sec
native strip reverse
f1(str1) === true;
f1(str2) === true;
f1(str3) === false;
for-loop character comparison
f2(str1) === true;
f2(str2) === true;
f2(str3) === false;
reverse half
f3(str1) === true;
f3(str2) === true;
f3(str3) === false;

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