hint [3/9]
Hint: 1
You may use regular expressions (RegExp) to remove unwanted characters from the string.
type
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hint [4/9]
Hint: 2
You may use Array.prototype.split and Array.prototype.join methods or for loop.
type
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hint [5/9]
Hint: 3
You may lowercase the string using String.prototype.toLowerCase.
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hint [6/9]
Spoiler Alert!
Solution ahead!
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hint [7/9]
First
function palindrome(str) {
var normalizedStr = str.replace(/[\W_]/g, '').toLowerCase();
var reverseStr = normalizedStr.split('').reverse().join('');
return normalizedStr === reverseStr;
}type
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/[\W_]/g
hint [1/9]
## :construction: After this are possible spoiler hints.
Make sure you've tried to hard to solve it yourself before proceeding. :construction:
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hint [1/9]
## :construction: After this are possible spoiler hints.
Make sure you've tried to hard to solve it yourself before proceeding. :construction:
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hint [2/9]
Explanation:
You have to check if the string you get as an input is a palindrome and return true if it is, and false otherwise.
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hint [3/9]
Hint: 1
You may use regular expressions (RegExp) to remove unwanted characters from the string.
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hint [4/9]
Hint: 2
You may use Array.prototype.split and Array.prototype.join methods or for loop.
type
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hint [1/12]
## :construction: After this are possible spoiler hints.
Make sure you've tried to hard to solve it yourself before proceeding. :construction:
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hint [2/12]
Explanation:
Our goal for solving this problem is tidying up the string passed in, and checking whether it is in fact a palindrome.
- If you are unsure of what a palindrome is, it is a word or phrase that when reversed spells the same thing forwards or backwards. A simple example is
mom, when you reverse the letters, it spells the same thing! Another example of a palindrome israce car. When we take out anything that is not a character it becomesracecarwhich is the same spelled forwards or backwards!
Once we have determined whether it is a palindrome or not we want to return either true or false based on our findings.
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hint [3/12]
Hint: 1
Regular expressions, RegEx, can be used to remove unwanted characters from the string.
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hint [4/12]
Hint: 2
The Array.prototype.split and Array.prototype.join methods can be of use here. For and while loops are another alternative, or why not even map!
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hint [5/12]
Hint: 3
String.prototype.toLowerCase can be used to make a string lowercase.
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hint [6/12]
Spoiler Alert!
Solution ahead!
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hint [7/12]
First Solution
function palindrome(str) {
return str.replace(/[\W_]/g, '').toLowerCase() ===
str.replace(/[\W_]/g, '').toLowerCase().split('').reverse().join('');
}type
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hint [8/12]
Second Solution
function palindrome(str) {
str = str.toLowerCase().replace(/[\W_]/g, '');
for(var i = 0, len = str.length - 1; i < len/2; i++) {
if(str[i] !== str[len-i]) {
return false;
}
}
return true;
}type
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hint [9/12]
Third Solution
(using recursion)
function palindrome(str) {
// make all letters lowercase and remove non-alphanumeric characters
str = str.toLowerCase().replace(/[^a-z|1-9]/g, "");
// if the length of the string is 0 then it is a palindrome
if (str.length === 0){
return true;
}
// if the first letter and the last letter of the string
// do not equal each other, then it is not a palindrome
if (str[0] !== str[str.length-1]){
return false;
}
//Else, run the function without the first and last characters.
else{
return palindrome(str.slice(1,str.length - 1));
}
}Code Explanation:
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hint [10/12]
First Solution
We start by using regular expressions to replace any white space or non-alphanumeric characters with nothing (or
null), which essentially removes them from the string.Next we chain
.toLowerCase()to remove any capital letters becauseAis a different character thana. The problem did not ask us to worry about making sure the case of the characters was identical, just the spelling.Our next step is to take our string and
.split()it,.reverse()it, and finally.join()it back together.Last step is to check that the string is the same forwards and backwards and return our result!
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