I am using felixge/node-mysql to run this query: "SELECT DISTINCT tablename.id FROM tablename"
The rows returned are (obviously) in this format: [{id: 123},{id: 234},{id: 345}]
I can't figure out how to get this: [123, 234, 345]
-
1developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… --- it must be the first thing you learn before you write any program in js. Also relevant: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…zerkms– zerkms2014-07-21 22:46:41 +00:00Commented Jul 21, 2014 at 22:46
-
Thanks for the tip @zerkms, I was just looking for a shorter way than looping and extracting myself.Karma– Karma2014-07-21 22:59:13 +00:00Commented Jul 21, 2014 at 22:59
-
you should have stated that explicitly, we obviously cannot read your minds. "I can't figure out" doesn't correlate with what you've just said.zerkms– zerkms2014-07-21 22:59:56 +00:00Commented Jul 21, 2014 at 22:59
Add a comment
|
2 Answers
With ES5, such is rather easy using a map transformation:
The map() method creates a new array with the results of calling a provided function on every element in this array.
For example:
var arr = [{id: 123},{id: 234},{id: 345}];
var res = arr.map(function (o) {
return o.id;
});
Doing this "manually" with a loop would look like so:
var arr = [{id: 123},{id: 234},{id: 345}];
var res = [];
// Loop over the array
for (var i = 0; i < arr.length; i++) {
var item = arr[i];
// And add new value we want to result array
res.push(item.id);
}
(Note that the variables are function-scoped, but I prefer to use "close placement" of var.)
1 Comment
zerkms
Upvoted because correct, but OP still won't become a better developer from this answer. Would be amazing if an alternative with explicit loop and array
.push() was added.You could use lodash or underscore:
var _ = require('lodash'); // or 'underscore'
var a = [{id: 123},{id: 234},{id: 345}];
var b = _.pluck(a, 'id');
console.log(b); // [123, 234, 345]
1 Comment
zerkms
Just a
.map() would be enough without requiring OP to bring a whole library for a trivial task.