How to get last item in array Node.js? [duplicate]

Question

I am new to node.js and JavaScript so this question might be quite simple but I cannot figure it out.

I have a lot of items in an array but only want to get the last item. I tried to use lodash but it somehow does not provide me with the last item in the array.

My array looks like this now:

images : ['jpg.item_1', 'jpg.item_2', 'jpg.item_3', ..., 'jpg.item_n']

and i want to get:

images : 'jpg.item_n'

Using lodash I am getting:

images : ['g.item_1', 'g.item_2', 'g.item_n']

It looks like I am just getting the last letter in jpg, i.e. 'g'.

My code using lodash looks like this:

const _ = require('lodash');

return getEvents().then(rawEvents => {

  const eventsToBeInserted = rawEvents.map(event => {
    return {

      images: !!event.images ? event.images.map(image => _.last(image.url)) : []

    }
  })
})

psilocybin · Accepted Answer · 2017-07-26 10:40:53Z

24

Your problem is that you're using _.last inside map. This will get the last character in the current item. You want to get the last element of the actual Array.

You can do this with pop(), however it should be noted that it is destructive (will remove the last item from the array).

Non-destructive vanilla solution:

var arr = ['thing1', 'thing2'];
console.log(arr[arr.length-1]); // 'thing2'

Or, with lodash:

_.last(event.images);

edited Jul 26, 2017 at 10:40

answered Jul 26, 2017 at 10:20

psilocybin

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2 Comments

Benjamin Andersen Over a year ago

I see, that makes sense. But how to I go about it when I want to get the result inside eventsToBeInserted?

psilocybin Over a year ago

You would do eventsTobeInserted.push(arr[arr.length-1])

Ved · Accepted Answer · 2017-07-26 10:31:18Z

2

Use .pop() array method

var images  =  ['jpg.item_1', 'jpg.item_2', 'jpg.item_3', 'jpg.item_n'];

var index= images.length - 1; //Last index of array
console.log(images[index]);

//or,

console.log(images.pop())// it will remove the last item from array

edited Jul 26, 2017 at 10:31

answered Jul 26, 2017 at 10:17

Ved

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2 Comments

NikxDa Over a year ago

This will remove the item though, so he should not.

Ved Over a year ago

@NikxDa correct. did not thoink of that. Thanks for pointing.

Dmitriy Simushev · Accepted Answer · 2017-07-26 10:20:56Z

0

Although Array.prototype.pop retrieves the last element of the array it also removes this element from the array. So one should combine Array.prototype.pop with Array.prototype.slice:

var images  =  ['jpg.item_1', 'jpg.item_2', 'jpg.item_3', 'jpg.item_n'];

console.log(images.slice(-1).pop());

answered Jul 26, 2017 at 10:20

Dmitriy Simushev

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4 Comments

Dmitriy Simushev Over a year ago

Any comments about the downvote? :)

Benjamin Andersen Over a year ago

I did this: images: !! event.images ? event.images.map(image => image.url.slice(-1).pop()) : [] but now I get an error saying TypeError: image.url.slice(...).pop is not a function. Not sure what that means?

Dmitriy Simushev Over a year ago

@BjarkeAndersen, most likely it's because the wrong format of event.images array. Make sure image.url is an array too. I've prepared a little working example for you: jsfiddle.net/enzam28p

Benjamin Andersen Over a year ago

Thanks @Dmitriy Simushev

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