Examples for reversing a string in JavaScript, Python and Dart

One of the most common interview questions is how do you reverse a string in the programming language that you know. Here are a few examples of how easily it can be done. As these programming languages are C based the syntax is quite similar so it is easy to translate across languages.

Example 1

JavaScript

function reverse(str) {
console.log(str.split('').reverse().join(''));
}
reverse('Hello World');

Python

def reverse(str):
print(''.join(reversed(str)));
reverse('Hello World');

Dart

void main() {
reverse(str) {
print(str.split('').reversed.join(''));
}
reverse('Hello World');
}

Example 2

JavaScript

function reverse(str) {
reversed = '';
for (let char of str) {
reversed = char + reversed;
}
console.log(reversed);
}reverse('Hello World');

Python

def reverse(str):
reversed = '';
for char in str:
reversed = char + reversed;
print(reversed);
reverse('Hello World');

Dart

void main() {
reverse(str) {
List newStrings = [];
dynamic index = (str.length);
while (index > 0) {
index -= 1;
newStrings.add(str[index]);
}
print(newStrings.join(""));
}
reverse('Hello World');
}

Example 3

JavaScript

function reverse(str) {    const arr = [];
for (let i = str.length - 1; i > -1; i--) {
arr.push(str[i]);
}
console.log(arr.join(''));
}
reverse('Hello World');

Python

def reverse(str):
new_strings = []
index = len(str)
while index:
index -= 1
new_strings.append(str[index])
print(''.join(new_strings))
reverse('Hello World');

Dart

void main() {
reverse(str) {
List arr = [];
for (var i = str.length - 1; i > -1; i--) {
arr.add((str[i]));
}
print(arr.join(''));
}
reverse('Hello World');
}

Example 4

JavaScript

function reverse(str) {    const arr = [];
for (let i = str.length - 1; i > -1; i--) {
arr.push(str[i]);
}
// Using regex
console.log(arr.toString().replace(/,/g, ''));
// Using reduce
console.log(arr.reduce((acc, cur) => acc + cur));
}reverse('Hello World');

Python

def reverse(str):
print(str[::-1]);
reverse('Hello World');

Dart

void main() {
reverse(str) {
List arr = [];
for (var i = str.length - 1; i > -1; i--) {
arr.add((str[i]));
}
// Using Reduce
print(arr.reduce((acc, curr) => acc + curr));
}
reverse('Hello World');
}

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Andrew Baisden

Andrew Baisden

⚛️ Software Developer @CGI_Global | 🌅 Technical Writer @ThePracticalDev @hashnode @Medium @LogRocket | 🎨 Content Creator | 📝 5k+ Blog Subscribers