Sort an array so that null values always come last
Check out .sort() and do it with custom sorting.
Example
function alphabetically(ascending) {
return function (a, b) {
// equal items sort equally
if (a === b) {
return 0;
}
// nulls sort after anything else
if (a === null) {
return 1;
}
if (b === null) {
return -1;
}
// otherwise, if we're ascending, lowest sorts first
if (ascending) {
return a < b ? -1 : 1;
}
// if descending, highest sorts first
return a < b ? 1 : -1;
};
}
var arr = [null, "a", "z", null, "b"];
console.log(arr.sort(alphabetically(true)));
console.log(arr.sort(alphabetically(false)));Use a custom compare function that discriminates against null values:
arr.sort(function(a, b) {
return (a===null)-(b===null) || +(a>b)||-(a<b);
});
For descending order of the non-null values, just swap a and b in the direct comparison:
arr.sort(function(a, b) {
return (a===null)-(b===null) || -(a>b)||+(a<b);
});