function stringReverse(str){
return str.split('').reverse().join('');
}
In an interview, i was asked to reverse a string. I solved it by above code but my interviewer said this is a bad solution. Then i used loop but he was not happy.
function stringReverse(str){
var a = str.split(''), b=[];
for(var i=0;i<arr.length;i++){
b.push(a[a.length-1-i]);
}
return b.join('');
}
Please add your comments.
May be interviewer wanted you to handle null, undefined or blank string
without this check your code might throw this exception
Cannot read property 'split' of undefined
use this :
if( str) {
str.split('').reverse().join('')
}
will evaluate to true if value is not:
OR more specifically :
if( str && (typeof str == 'string') ) {
// do something
}
refer this SO post for more details.
if(typeof str == 'string'). Otherwise, an error would be thrown if the value is an object, number, etc.
There are two possible ways your interviewer might not have been happy with your answer.
From my experience, when an interviewer asks you to reverse a string, you shouldn't use the existing functions for it. You should implement it from scratch. In your case, a nice approach would be to use recursion to solve the problem. Look at this link!
Performance issues! Using the reverse function is not the fastest way to reverse a string. Check this out!
Hope this solved your questions :)
This article deals with unicode symbols in JavaScript: JavaScript has a Unicode problem · Mathias Bynens
The best solution to your problem uses the Array.from method which works in all browsers except from Internet Explorer (MDN has a polyfill for that).
Here is a solution based on the articles answer to reverse a string:
function strReverse(str) {
//Only allow numbers and strings to pass, else return empty string
if (typeof str != 'string' && typeof str != 'number') {
return '';
}
//Return the reversed string
return Array.from(str.toString()).reverse().join('');
}
//TESTS
console.log([
strReverse(),
strReverse(null),
strReverse("null"),
strReverse(true),
strReverse("▼ ▼▲ ▼"),
strReverse(1138),
strReverse('𝌆'),
strReverse('f𝌆ff𝐀'),
]);In ECMAScript 6, you can reverse string like as below
var string = "hello";
var str = [...string].reverse().join('');
console.log(str);
When I was in 10th standard, Our computer teacher always asks every student to write a code to check if the given string is palindrome or not.
Palindrome string is a string which is always same as its reverse ex: mom = mom
In an interview, if someone asked you to write a code to reverse a string. Then he wants to see your logical approach to solve the problem. Existing function in any programming language has also code which actually put a logical approach and solves the problem.
Reverse code in java
import java.util.*;
class Reverse
{
public static void main(String args[])
{
String original, reverse = "";
Scanner in = new Scanner(System.in);
System.out.println("Enter a string to get reverse");
original = in.nextLine();
int length = original.length();
for ( int i = length - 1; i >= 0; i-- )
reverse = reverse + original.charAt(i);
}
}
String words[] = str.split("\\s");
String rev = "";
for (String w : words) {
StringBuilder sb = new StringBuilder(w);
sb.reverse();
rev += sb.toString() + " ";
}
System.out.println("\n reverse string=" + rev);
java while the question was about javascript unfortunately.
"Easy: 😎"