Palindrome Checker freecodecamp Problem

JavaScript
1

Hi guys Ive done the proyect in vscode i tried the code and it worked then I pasted the code inside freecodecamps and its saying some of the test doesnt provide the correct solution. I typed every test in my vscode editor and every test answed the question correctly. The following are the test`s i checked.

console.log(palindrome(“eye”));

console.log(palindrome(“_eye”));

console.log(palindrome(“race car”));

console.log(palindrome(“not a palindrome”));

console.log(palindrome(“A man, a plan, a canal. Panama”));

console.log(palindrome(“never odd or even”));

console.log(palindrome(“nope”));

console.log(palindrome(“almostomla”));

console.log(palindrome(“My age is 0, 0 si ega ym.”));

console.log(palindrome(“1 eye for of 1 eye.”));

console.log(palindrome(“0_0 (: /-\ :slight_smile: 0-0”));

console.log(palindrome(“five|_/|four”));

and every answer matched but not in freecodecamp

Can someone help me please? thanks!

2

Please post the full code and the link to the challenge as well.

3 
function palindrome(str) {
    let upSideStr=[ ];
    let normalStr=[];
    for(let i=0; i<str.length; i++){
        if(isNumOrLetter(str[i])==false){
            str[i]=" ";
        }else{
            normalStr.push(str[i].toLowerCase());
            
            upSideStr.unshift(str[i].toLowerCase());
        }
    }
    console.log(upSideStr);
    console.log(normalStr);
    return isEqual(upSideStr,normalStr);
  }
  
  function isNumOrLetter(a){
    let question;
    let aNumber=parseInt(a);
    a.charCodeAt(a)>=97&&a.charCodeAt(a)<=122 ? question=true:
    a.charCodeAt(a)>=65&&a.charCodeAt(a)<=90 ? question=true:
    aNumber>=0&&aNumber<=9 ? question=true:
    question=false;
    return question;
  }

function isEqual(str1,str2){
    let isTrue=true;
    for(let i=0; i<str1.length&&isTrue==true; i++){
        str1[i]==str2[i] ? isTrue=true:
        isTrue=false;
    }
    return isTrue;
}

console.log(palindrome("eye"));
console.log(palindrome("_eye"));
console.log(palindrome("race car"));
console.log(palindrome("not a palindrome"));
console.log(palindrome("A man, a plan, a canal. Panama"));
console.log(palindrome("never odd or even"));
console.log(palindrome("nope"));
console.log(palindrome("almostomla"));
console.log(palindrome("My age is 0, 0 si ega ym."));
console.log(palindrome("1 eye for of 1 eye."));
console.log(palindrome("0_0 (: /-\ :) 0-0"));
console.log(palindrome("five|\_/|four"));
4

Do you see this error

true
TypeError: 0 is read-only

5

This, by the way, is an anti-practice. The ternary is not a general purpose replacement for if.

6

Is this line legal code?

I would not trust your VSCode, as this should never be allowed in JS. Something must be broken on your computer.

7

I changed it with str[i]=String.fromCharCode(32) and it keeps giving me the same results on vs code the correct answers in freecodecamp in most of the cases fails the test

8

Thanks for the advice, in which cases i should use ternary?. I know i haven`t use the best practices, i havent finished the course in freecamp but i wanted to take the challenge for the fun of it. I will do it again once i finish the course.

9

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No, i dont

10

You can not mutate a string. All primitives are immutable.

const firstName = "John"
firstName[0] = "L"
console.log(firstName) // John

const age = 42
age[0] = 5
console.log(age) // 42

If you want to change a string you have to create a new one, which is why String methods return a new string.

Edit: Do note that it is not a syntax error and no error is thrown unless you are in strict mode (the challenges run in strict mode).

"use strict";
const firstName = "John"
firstName[0] = "L" // Cannot assign to read only property '0' of string 'John'
console.log(firstName)
1 Like
11

But i dont use strings i use arrays and they are indeed new

12

Right here this is you attempting to mutate a string

1 Like
13

My bad i took that line that is wasnt necessary at all and changed the NumOrLetter function with the regex mode. Thanks everyone giving me a hand!

function palindrome(str) {

    let upSideStr=[];
    let normalStr=[];

    for(let i=0; i<str.length; i++){
        if(isNumOrLetter(str[i])==true){
            normalStr.push(str[i].toLowerCase());
            upSideStr.unshift(str[i].toLowerCase());
        }
    }
    console.log(upSideStr);
    console.log(normalStr);
    return isEqual(upSideStr,normalStr);
  }
  
  
  function isNumOrLetter(a){
    let question;
    let regex=/[a-zA-Z0-9]/;
    return regex.test(a);
  }



function isEqual(str1,str2){
    let isTrue=true;
    for(let i=0; i<str1.length&&isTrue==true; i++){
        str1[i]==str2[i] ? isTrue=true:
        isTrue=false;
    }
    return isTrue;

}

14 
str1[i] == str2[i] ? isTrue = true: isTrue = false;

When you do an assignment using a ternary you should do it on the left side of it.

const isAuthed = true;
const route = isAuthed ? '/admin' : '/signin'
console.log(route) // '/admin'

Personally, I would always avoid variable assignments inside the expressions. Although, you do see it from time to time I don’t really think it is the correct use of a ternary.

If you need to do assignments to more than one variable I would suggest not using a ternary.

1 Like
15

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