Using JavaScript, I would like to know how to sort lexicographically an array of objects based on a string value in each object.
Consider:
[
{
"name" : "bob",
"count" : true
"birthday" : 1972
},
{
"name" : "jill",
"count" : false
"birthday" : 1922
},
{
"name" : "Gerald",
"count" : true
"birthday" : 1920
}
]
How can I sort the array alphabetically by name?
The name values are usernames, so I would like to maintain the letter casing.
var obj = [...];
obj.sort(function(a,b){return a.name.localeCompare(b.name); });
Be aware that this will not take capitalisation into account (so it will order all names beginning with capitals before all those beginning with smalls, i.e. "Z" < "a"), so you might find it relevant to add a toUpperCase() in there.
You can make it more generic as well:
function sortFactory(prop) {
return function(a,b){ return a[prop].localeCompare(b[prop]); };
}
obj.sort(sortFactory('name')); // sort by name property
obj.sort(sortFactory('surname')); // sort by surname property
And even more generic if you pass the comparator to the factory...
toLocaleUpperCase/toLocaleLowerCase instead of toUpperCase/toLowerCase.
["a", "A", "b", "B"].sort((a,b)=>{return a.localeCompare(b)}) expected to be ["A", "B", "a", "b"] but returns ["a", "A", "b", "B"]
'aaA'.localeCompare('aAA') returns -1 which sorts aaA before aAA which is incorrect in the case of lexicographic orderThis will do it:
arr.sort(function(a, b) {
return a.name.localeCompare(b.name);
});
Using comparison
arr.sort(function (a, b) {return a.name.toLowerCase() > b.name.toLowerCase()})
https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String#Comparing_strings
I read in this post sort array lexicographically in javascript to just use sort directly and not localeCompare and this seems to do the trick.
localeComparedoes not sort lexicographically.
'aaA'.localeCompare('aAA') returns -1 which sorts aaA before aAA. In lex, capitals come first, so it should be ['aAA', 'aaA']
You can do something like this to handle a few cases.
export default function sortLex ({ arr, prop, reverse }) {
let sorted
if (prop) {
sorted = arr.sort(sortFactory(prop))
} else sorted = arr.sort(sort)
return reverse ? sorted.reverse() : sorted
}
function sort (a, b) {
if (a < b) {
return -1
}
if (a === b) {
return 0
}
if (a > b) {
return 1
}
}
function sortFactory (prop) {
return (a, b) => {
return sort(a[prop], b[prop])
}
}
sort() function, what happens if a and b are not ordered?