Check if the value of key in an array of objects is same - Lodash - lodash

Question

Want to check if either the values of all rows in the array of objects is same or the values of all columns in the array of objects is same. How do I efficiently do this with lodash?
[
{row: 0, col: 4},
{row: 0, col: 1},
{row: 0, col: 2}
]
In the above case all rows in the array of objects is same.

Answer 1

If I understood the constraints correctly, how about this?
var data = [
{row: 0, col: 4},
{row: 0, col: 1},
{row: 0, col: 2},
];
function allTheSame(data, key) {
return data.length && _.every(data, function (item) {
return item[key] === data[0][key];
});
}
console.log(_.any(['row', 'col'], function (key) {
return allTheSame(data, key);
}));
Note that _.every and _.any both bail out early, so this should be about as efficient as possible.
Also note that allTheSame returns false if there are no elements in the array. You could switch to return data.length === 0 || _.every(... instead if you want an empty list to be considered "all the same."

Answer 2

The tricky part is trying to check if both column or row values are the same, in the same iteration with lodash. However, that shouldn't be necessary unless your are dealing with an unspeakable amount of data. Assuming that is not the case, here's simple, linear approach:
function isRowOrColSame(data) {
var row = _.every(data, {'row': data[0].row})
var col = _.every(data, {'col': data[0].col})
return (row || col)
}
var data = [
{row: 0, col: 4},
{row: 0, col: 1},
{row: 0, col: 2}
]
console.log(isRowOrColSame(data))
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.13.1/lodash.min.js"></script>
If you need an explanation as to what's going on with the every function, let me know. I hope that helps!