How can i sort array in Javascript based on the first characters of the string element of the array ? - javascript

Question

i am this array:

var notifiche_eq= ["10/avdvidv","15/jcbscisb","7/ciudsu"];

and i would this output:

["15/jcbscisb","10/avdvidv","7/ciudsu"]

so based on numeric characters of each element.

I tried this code but doesn't work:

var notifiche_eq= ["10/avdvidv","15/jcbscisb","7/ciudsu"];

notifiche_eq.sort(function(a, b) {
    var milliA= notifiche_eq[a].split('/');
    var milliB= notifiche_eq[b].split('/');

    milliA= (milliA[0])+0;
    milliB= (milliB[0])+0;

    if(milliB- milliA){
     return b-a;
    }

}); 

alert(notifiche_eq);

here there's jsfiddle: https://jsfiddle.net/13tLjqc0/8/

I hope you can help me and sorry for my english :/

Zenoo · Accepted Answer · 2018-03-02 10:44:33Z

1

You don't need to use notifiche_eq[a]. a is already your item.

I optimized your code, so that it handles >, < and ==

var notifiche_eq= ["10/avdvidv","15/jcbscisb","7/ciudsu"];

notifiche_eq.sort(function(a, b) {
  return (+a.split('/')[0] > +b.split('/')[0] ? -1 : (+a.split('/')[0] < +b.split('/')[0] ? 1 : 0));
}); 

console.log(notifiche_eq);

Version without any ternary operators like asked in the comments :

var notifiche_eq= ["10/avdvidv","15/jcbscisb","7/ciudsu"];

notifiche_eq.sort(function(a, b) {
  if(+a.split('/')[0] > +b.split('/')[0]) return -1;
  else if(+a.split('/')[0] < +b.split('/')[0]) return 1;
  else return 0;
}); 

console.log(notifiche_eq);

edited Mar 2, 2018 at 10:44

answered Mar 2, 2018 at 10:21

Zenoo

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1 Comment

Borja Over a year ago

please can you show me code not using ternary operator ? Thanks a lot :)

gurvinder372 · Accepted Answer · 2018-03-02 10:24:03Z

1

a is already the item of the array, instead of its index so this line is wrong

var milliA= notifiche_eq[a].split('/');

Instead just simply

split the item of the array
get first index value
convert that to number using unary +

i.e.

notifiche_eq.sort(function(a, b) {
  return +b.split('/')[0] - +a.split('/')[0];
});

answered Mar 2, 2018 at 10:24

gurvinder372

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Comments

void · Accepted Answer · 2018-03-02 10:24:19Z

1

Issues you had...

notifiche_eq[a] and notifiche_eq[b] should be just a and b.
Just return b-a.

var notifiche_eq= ["10/avdvidv","15/jcbscisb","7/ciudsu"];

notifiche_eq = notifiche_eq.sort(function(a, b) {
    var milliA= a.split('/');
    var milliB= b.split('/');

    milliA= +milliA[0];
    milliB= +milliB[0];

    return milliB - milliA;

}); 

console.log(notifiche_eq);

You can do some fancy things on your code to make it look good... like..

notifiche_eq.sort((a, b) => +b.split('/')[0] - +a.split('/')[0]);

answered Mar 2, 2018 at 10:24

void

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Comments

Medet Tleukabiluly · Accepted Answer · 2018-03-02 10:24:23Z

1

var notifiche_eq = ["10/avdvidv", "15/jcbscisb", "7/ciudsu"];

// es5
notifiche_eq.sort(function (a, b) {
    return b.split('/').shift() - a.split('/').shift()
});
// es6
notifiche_eq.sort((a, b) => b.split('/').shift() - a.split('/').shift());

console.log(notifiche_eq)

answered Mar 2, 2018 at 10:24

Medet Tleukabiluly

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Comments

Faly · Accepted Answer · 2018-03-02 10:25:16Z

1

Split by /, take the first element and convert it to number by using +

var notifiche_eq= ["10/avdvidv", "15/jcbscisb", "7/ciudsu"];
notifiche_eq.sort((a, b) => +b.split('/')[0] - +a.split('/')[0]);
console.log(notifiche_eq);

edited Mar 2, 2018 at 10:25

answered Mar 2, 2018 at 10:21

Faly

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1 Comment

Weedoze Over a year ago

Good answer, you should perhaps add an explanation about why notifiche_eq[a] is incorrect

Nina Scholz · Accepted Answer · 2018-03-02 10:26:27Z

1

You could use a regular expression for getting the starting digits of the string.

var notifiche_eq = ["10/avdvidv","15/jcbscisb","7/ciudsu"];

notifiche_eq.sort(function (a, b) {
    function getValue(s) { return s.match(/^\d+/)[0]; }
    return getValue(b) - getValue(a);
});

console.log(notifiche_eq);

answered Mar 2, 2018 at 10:26

Nina Scholz

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