I have array containing random numbers. When I trying to sort this array via .sort() method, the result is different if array contains duplicate numbers. The code below works differently in Chrome and Firefox:
[1,2,3,4,5,6,7,8,9,2,15,3,4,5,1,2,3,4,0,2,3].sort(function(a, b) {
console.log("a=", a, "b=", b)
})
Plunker: http://plnkr.co/edit/Ocm1ZSXgkoCM7FQeH0v5
Does it bug ? How to fix this behavior to have same result in Chrome and FF ?
It works with a proper return value.
var array = [1,2,3,4,5,6,7,8,9,2,15,3,4,5,1,2,3,4,0,2,3];
array.sort(function(a, b) {
return a - b;
});
console.log(array);
array.sort(function(a, b) {
return (a & 1) - (b & 1) || a - b;
});
console.log(array);.as-console-wrapper { max-height: 100% !important; top: 0; }
1 and 3 to be different then they might or might not get shifted along. If you want the sorting to be stable, use a stable sorting function. Right now you are not allowing JS to sort it correctly because different inputs produce a different output.Since sort() is not necessarily stable, you need to save the position of an element before sorting and use it as compare parameter if the value is equal, if you want to keep the position in the result array . But the problem in your case is, you have multiple values and can't just look up the position in the starting-array. You need to wrap your values in objects:
var values= [1,2,3,4,5,6,7,8,9,2,15,3,4,5,1,2,3,4,0,2,3];
var wrappedValues = [];
//first create wrapped values
for(var i = 0;i < values.length;i++){
wrappedValues.push({value : values[i], index : i});
}
//now sort wrapped values
wrappedValues.sort(function(a, b) {
var result = a.value % 2 - b.value % 2;
if(result == 0){
return a.index - b.index;
}
return result;
});
//now unwrappe the values:
var unwrappedValues = [];
wrappedValues.forEach(function(entry) {
unwrappedValues.push(entry.value);
});
console.log(unwrappedValues );btw. part of your Problem is in the compare function from the answer you provided:
return a % 2 - b % 2 || a - b;
this function is sorting ascending in || a - b - part
.map(/* decorate */).sort().map(/* undecorate */) which avoids declaring the intermediate temporary values..map() creates a new Array, so how would this avoid declaring the intermediate temporary values? o.OwrappedValues is merely noise. Similarly, the name unwrappedValues is also just noise - do you really, honestly care that the values were once wrapped in something when they are presented as plain values again?
sortfunction is wrong. Since it returnsundefinedfor every single comparison, it's expected that sorting won't work.