I have this data:
[
{foo: 1, bar: a},
{foo: 2, bar: b},
{foo: 3, bar: c},
]
What's the simplest way to transform the data to something like
{
customLabel1 : [1,2,3],
customLabel2 : [a,b,c]
}
I come up with this
{
customLabel1: data.map((a) => {return a.foo} ),
customLabel2: data.map((a) => {return a.bar} )
}
Is there a simpler way to do this, or faster?
If you want simpler, your code is already pretty close with fat arrow syntax. You can drop the parentheses and the return keyword:
{
customLabel1: data.map(a => a.foo),
customLabel2: data.map(a => a.bar)
}
If you want faster, I think you'll have to sacrifice some simplicity. As it's written, you're looping over data twice. If you iterated once, it would look something like this:
var data = [
{foo: 1, bar: 'a'},
{foo: 2, bar: 'b'},
{foo: 3, bar: 'c'},
];
var o = {customLabel1: [], customLabel2: []};
data.forEach(a => {
o.customLabel1.push(a.foo);
o.customLabel2.push(a.bar);
});
console.log(o);You can use this form if you dont know the keys
{
customLabel1: data.map(function(element) { return element[Object.keys(element)[0]];}),
customLabel2: data.map(function(element) { return element[Object.keys(element)[1]];})
}
You could use an object for the key mapping and iterate then.
var data = [{ foo: 1, bar: 'a' }, { foo: 2, bar: 'b' }, { foo: 3, bar: 'c' }],
labels = { customLabel1: 'foo', customLabel2: 'bar' },
result = {};
data.forEach(a => Object.keys(labels).forEach(k => {
result[k] = result[k] || [];
result[k].push(a[labels[k]]);
}));
console.log(result);The shorter syntax of the map call can be:
data.map(el => el.prop);
Having said that, I'd define a helper function for this:
function pluck(arr, props) {
return Object.keys(props).reduce((ret, prop) => {
ret[prop] = arr.map(el => el[props[prop]]);
return ret;
}, {});
}
var ret = pluck(data, {
customLabel1: 'foo',
customLabel2: 'bar'
});
return..customLabel1: data.map((a) => (a.foo))