Node.JS string array sort is not working

Question

Hi I am absolute beginner of node.js Today I tried the following code

var fs, arr;
var dir, str;
var cont, item;

fs=require('fs');
cont=fs.readFileSync('unsort.txt').toString();
arr=cont.split('\n');
arr.sort();

for(str=arr.shift();str&&(item=arr.shift());)
    str+='\n'+item;
fs.writeFileSync('sort_by_script.txt', str);

the above node.js code reads a file as string, from the directory of the node.exe. Splits the string by newline ('\n') to get a array. Sorts the array and prints the sorted array to the file. So as a whole the script reads a file sort the entries and saves the sorted entry in another file. The problem is the sorted order is not correct. I tried sorting the content of unsort.txt manually using MS Excel by which I got the correct order of sort. Can any one help me why the arr.sort() is not working correct. You can download unsort.txt, sort_by_script.txt, sort_by_ms_excel.txt and node.exe in the package [Sort.rar][1]

Note : unsort.txt has no numbers. All are only alphabets.

Examples from unsort.txt:

appjs
gbi
node
frame
require
process
module
WebSocket
webkitAudioContext
webkitRTCPeerConnection
webkitPeerConnection00
webkitMediaStream
MediaController
HTMLSourceElement
TimeRanges

sort by what? Are you aware that you sort strings and not numbers? — pfried
– pfried, Commented Apr 4, 2013 at 7:00
can you describe the content of the file and how you want to sort it? Please post it here, the download wont work forever (and is not working at the moment) — pfried
– pfried, Commented Apr 4, 2013 at 7:01

pfried · Accepted Answer · 2013-04-04 07:34:11Z

12

If you do not pass a custom search function the sort function sorts lexically, numbers get cast to strings and so it happens that e.g. "10" is before "3". So the strings get sorted.

You can pass a custom function to the sort function which decides the order of the items, in case of numbers this would be an example (Be careful as numbers in your example would be strings if you dont cast / parse them to numbers) :

var numsort = function (a, b) {
    return a - b;
}

var numbers = new Array(20, 2, 11, 4, 1);

var result = numbers.sort(numsort);

Another example for strings:

var sortstring = function (a, b)    {
    a = a.toLowerCase();
    b = b.toLowerCase();
    if (a < b) return 1;
    if (a > b) return -1;
    return 0;
}

edited Apr 4, 2013 at 7:34

answered Apr 4, 2013 at 7:10

pfried

5,1192 gold badges42 silver badges79 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Dinesh Over a year ago

but unsort.txt has no number at all. All are only alphabets.

pfried Over a year ago

please post the contents here. it was a guess and an example, your google folder cant be opened and it wont be there forever (in opposite to this question)

Dinesh Over a year ago

you can try to download now its in a different link

pfried Over a year ago

post them here, it is easy to do even if it is only an extract of the file

Dinesh Over a year ago

the file has 564 line of entries. If I post it here it would make a mess. I think the download should be working now. Try again.

|

Mark Mulder · Accepted Answer · 2017-08-24 12:59:26Z

4

I would use

arr.sort((obj1, obj2) => {
            return obj1.localeCompare(obj2);
        });

That will most likely solve your issue.

answered Aug 24, 2017 at 12:59

Mark Mulder

662 bronze badges

Collectives™ on Stack Overflow

Node.JS string array sort is not working

2 Answers 2

7 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

7 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related