One of these occurs when I want to sort an array of numbers.
Ex:
var a = [44,7,5,6,4,2,1];
a.sort();
console.log(a);
The expected result would be:
[1, 2, 4, 5, 6, 7, 44], but what is always returned to me is [1, 2, 4, 44, 5, 6, 7].
This is a very small array , but the one I'm working on (with over 300 occurrences) has been the same. 115 appears before 2, for example.
To order precise numbers to pass a method comparison function.
Test with
function(a, b) {
return a - b;
}
The return of this function is what indicates to the method the position of the element in relation to what is being compared.
That is:
var a = [44,7,5,6,4,2,1];
a = a.sort(function(a, b) {
return a - b;
});
console.log(a); // dá [1, 2, 4, 5, 6, 7, 44]
As @bigown specified the comparison the method does (without giving it a function) does not what do you think The official specification is :
If you comparefn is not undefined and a consistent comparison function for the elements of this array (see below), the behavior of sort is implementation-defined.
In other words, when a function is not passed, what is done is at your browser's convenience. In MDN it is said that the values will be treated as String and I think this is what the biggest pare of browsers does. ( read more at MDN in English here )
JavaScript treats elements as string , so the "problem" happens. Solution:
var a = [44, 7, 5, 6, 4, 2, 1];
a.sort(function(a, b) { return a - b; });
document.body.innerHTML += a You can do the following to sort correctly by passing a callback function as a parameter to the sort function:
var a = [44,7,5,6,4,2,1];
a.sort(function(a, b) {
return a - b;
});
document.write(a);
//console.log(a);Or it could also do this:
var a = [44,7,5,6,4,2,1];
a.sort(function(a, b){
return a > b;
});
document.write(a);