如何将数组的值添加到对象

Question

I've got code which splits the key and value at the = sign at end if line, the problem is that I have lines which have more then one =

For example:

user = aaaa
userb = bbbb
userc = test
userd = foo = bar = test 

I read file with node fs and I divide it to the key and value at the = so userd causes a problem.

I am using var array = line.split('=');

Then I assign it to object in the loop

myobj = {}

myobj[array[0]] = array[1];

This is working (my obj in the loop contains all the users) until I get to userD . So how can I concatenate all the values of userD to myObj

Answer 1

If we assume that everything after the first = sign is the value, regardless of whether theres another = sign then you can do this:

myobj[array[0]] = array.slice(1).join(' = ');

Now, if you want to store it simple as an array of equal values, you can do:

myobj[array[0]] = array.slice(1);

The slice function returns the same array starting at the element passed (it does more but thats what it's for here).

Update I didn't think of this answer but it's even a bit faster!

Answer 2

Have a look at Array.prototype. shift() Array.prototype. shift() :

myobj[array.shift()] = array;

Unlike Array.prototype. splice() Array.prototype. splice() , shift() won't create an entirely new array in order to wrap up the one value we're trying to extract. See my comment here .

Here are the results from a performance test ; it shows operations per second (higher is better):

Chrome 44.0.2403                                4,290,938   3,993,798   1,042,423
Chrome 46.0.2468                                3,631,277   4,020,712   1,098,866
Firefox 38.0                                    1,706,068   1,419,219   895,714
Firefox 40.0                                    1,739,110   1,508,623   955,794
IE 11 in Compatibility Mode 10.0.0              3,393,698   2,855,417   1,721,229

According to these results, shift() is the fastest with slice() right behind. splice() , on the other hand, is a good bit slower than both... mainly because it's ill-suited to this particular task.

That said, I was surprised. I expected this answer to be the fastest.

Answer 3

Use splice function:

myobj[array.splice(0, 1)] = array;

This will cut the first item out of your array and return it as myobj parameter, the rest is going to be kept in the array, so you can either use array as an object property or let's say join it to a string:

myobj[array.splice(0, 1)] = array.join(", ");