First clear solution for [old] Median by Sim0000 - javascript coding challenges

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First solution in Clear category for [old] Median by Sim0000

"use strict";

function median(data) {
    data = data.sort((a, b) => a - b)
    n = Math.floor(data.length / 2)
    return (data[n] + data[data.length - 1 - n]) / 2
}

var assert = require('assert');

if (!global.is_checking) {
    assert.equal(median([1, 2, 3, 4, 5]), 3, "1st example");
    assert.equal(median([3, 1, 2, 5, 3]), 3, "2nd example");
    assert.equal(median([1, 300, 2, 200, 1]), 2, "3rd example");
    assert.equal(median([3, 6, 20, 99, 10, 15]), 12.5, "4th example");
    console.log("Coding complete? Click 'Check' to review your tests and earn cool rewards!");
}

July 7, 2016

Comments:

ZoltanOnody on July 21, 2016, 10:12 a.m.
Nice, btw. I am new to JS, so I have 2 questions. 1. When is it OK not to use semicolons? 1. If you don't declare a variable using var/let/const what's happening then? Obviously it works but I have no idea why.

Sim0000 on July 21, 2016, 3:34 p.m.
I am newbie too :-) > 1. When is it OK not to use semicolons? My understand, semicolon can be omitted if the statement is followed by a new line. See more detail by article <a href="https://www.codecademy.com/blog/78">Your Guide to Semicolons in JavaScript</a>. > 2. If you don’t declare a variable using var/let/const what’s happening then? Obviously it works but I have no idea why. Undeclared variable is global. See <a href="https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/var">MDN</a>.

cyw617 on Sept. 16, 2016, 4:21 p.m.
Love your solution. It will be perfect if variables are declared before being used =P And it is usually better not to re-assign the input variables.

pythondetective on Sept. 17, 2016, 7:57 p.m.
Good solution. I run the program with no var keyword in front of n. I receice error message; undeclared variable.

Vikky on Feb. 28, 2017, 1:40 p.m.
If "use strict" is used you must declare the variable or you'll get the error. Without "use strict" it works. You can read about "use strict" here: <a href="https://www.w3schools.com/js/js_strict.asp">https://www.w3schools.com/js/js_strict.asp</a>

Sim0000 on Feb. 28, 2017, 4:14 p.m.
Thank you for your comment. In beta test period, "use strict" did not work correctly. Currently it is functioning properly.

Papygorgio on April 30, 2017, 3:51 p.m.
I think you could simply use <pre class='brush: javascript'>data.sort((a, b) => a-b) </pre> Instead of <pre class='brush: javascript'>data = data.sort((a, b) => a - b) </pre> Nice solution nonetheless :)

Sim0000 on May 1, 2017, 5:51 a.m.
Thank you!

elhay-av on June 7, 2017, 7:14 p.m.
in addition you should perform sort on new array, to leave original array as is, so: <pre class='brush: javascript'>data = data.slice().sort((a, b) => a - b) </pre> no we have in data reference to new sorted array. and original array not changed

LazyFox on July 23, 2019, 8:38 a.m.
That's wrong! Check it! <pre class='brush: javascript'>function median(data) { data = data.sort((a, b) => a - b) n = Math.floor(data.length / 2) return (data[n] + data[data.length - 1 - n]) / 2 } let tmp = [3, 6, 20, 99, 10, 15]; console.log(tmp); // [ 3, 6, 20, 99, 10, 15 ] median(tmp); console.log(tmp); // [ 3, 6, 10, 15, 20, 99 ] WTF? </pre> Use somthing like this: <pre class='brush: javascript'>let data = data.slice().sort((a,b) => a - b); </pre>

zwelden on May 30, 2017, 6:48 p.m.
Elegant solution. That last line replaces nearly half of the code I wrote. Very nice.

pDestiny on Dec. 30, 2017, 5:57 a.m.
I hate your solution cz better than mine

AlyoKizz on March 20, 2018, 7:49 a.m.
ВАУ...<3

ijklim on April 3, 2018, 10:25 p.m.
data variable is mutated this way, to avoid side effect would it be cleaner to clone the data array first?

ijklim on April 3, 2018, 10:26 p.m.
data variable is mutated this way, to avoid side effect would it be cleaner to clone the data array first?

Sim0000 on April 5, 2018, 1:44 a.m.
data = data.slice().sort((a, b) => a - b)

Tairraos on June 1, 2018, 4:34 a.m.
`data[n - 1]` and `data[data.length - 1 - n]` is the same item

Sim0000 on June 1, 2018, 7:06 a.m.
The situation changes depending on whether data.length is odd or not. <pre class='brush: javascript'>data.length = 5, n = 2, n - 1 = 1, data.length - 1 - n = 2 # odd case, different data.length = 6, n = 3, n - 1 = 2, data.length - 1 - n = 2 # even case, same </pre>

Tairraos on June 1, 2018, 7:51 a.m.
odd case just need return the middle item, only should calculating for even case.

Sim0000 on June 1, 2018, 4:54 p.m.
I don't understand what you say. What is data[n - 1]?

Tairraos on June 2, 2018, 4:24 a.m.
my bad.... :( your solution is smart. i used ternary expression and excluded odd items case. so there's only even items case in my mind. now i got your talent thinking, the length-n-1 both work on even and odd case... sorry for my careless reply.

Sim0000 on June 2, 2018, 5:05 a.m.
Thanks. Now I got it :-)

nlupton on June 14, 2018, 8:38 p.m.
A concise and clear solution - the only changes I would personally make would be to declare n (ie 'let n =') as this will end up as a global variable, also data.sort() will mutate the original array, so copying the array before sorting would be better practise.

Sim0000 on June 15, 2018, 4:41 a.m.
Thank you. Good point!

ug.dotenko on Aug. 21, 2018, 8:39 a.m.
Nice! Why to bother about odd and even length?! Just calculate it!

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