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I have an array of different exercises: 

exercises: {
  push: ['Push up', 'Bench press'],
  legs: ['Squat', 'Power squats'],
  pull: ['Pull up', 'Chin up'],
  cardioCore: ['Running high knees', 'Plank']
}

How can I combine all of these into a single array or object? I need to create this:

allExercises: ['Push up', 'Bench press', 'Squat', 'Power squats', 'Pull up', 'Chin up', 'Running high knees', 'Plank']

I'm also going to sort alphabetically so the order isn't important.

I think I could do this with a forEach, something like this: 

let allExercises = [];
exercises.forEach(exerciseGroup=>{
  allExercises.push(exerciseGroup);
});

But this feels a bit messy. Is there a nicer ES6 solution?

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1
  • Use .concat(). Commented Nov 7, 2017 at 3:43

5 Answers 5

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2

Yes, just use Object.values and Array.prototype.reduce.

const allExercises = Object.values(exercises)
  .reduce((array, subarray) => array.concat(subarray), []);
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4 Comments

Personal preference, but instead of .concat function, one can also use the ... (spread) operator
Also, is Object.values part of ES6 or ES7, just curious
@AyushGupta Hm… it’s actually ES8, but it can easily be polyfilled or replaced by a Object.keys approach.
Yeah, was just curious because this call once failed in node 6.10 xD
2

Here's another way, ES6 compatible.:

Object.getOwnPropertyNames(exercises)
.reduce((allExercises, exerciseName) => [...allExercises, ...(exercises[exerciseName])], [])

As @stealththeninja said, you can also do this to reduce a bunch of overhead.

Object.getOwnPropertyNames(exercises).reduce((allExercises, exerciseName) => {
  allExercises.push(...exercises[exerciseName]);
  return allExercises;
}, []);
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5 Comments

[...all, ...exercises[name] returns a new array each time. Reduce passes the object (or array) by reference, why not add the items and return all? all.push(...exercises[name]); return all;
You could, I just prefer the spread approach. One liner returns seem cleaner.
One liner returns seem cleaner. Cleaner syntactically but wasteful creating a new array for each property name.
Hmm, yeah. Edited the answer to add your suggestion as an alternative, thanks!
Thanks for considering the feedback, I appreciate it. :)
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My ugly solution:

  let combineExercises = [];

  Object.values(allExercises).forEach((exerciseGroup) => {
    exerciseGroup.forEach((exercise) => {
      combineExercises.push(exercise)
    })
  });

  console.log(combineExercises);
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Comments

0

You can use Object.values & spread operator

var exercises = {
    push: ['Push up', 'Bench press'],
    legs: ['Squat', 'Power squats'],
    pull: ['Pull up', 'Chin up'],
    cardioCore: ['Running high knees', 'Plank']
}
var allexercise ={},tempArray=[];
for(var keys in exercises){

    tempArray.push(...Object.values(exercises[keys]))
}
allexercise=tempArray;

console.log(allexercise)

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0 
[].concat.apply([], Object.values(exercises));
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7 Comments

What's the need for .join(',').split(',')?
.join joins nested arrays as if they are flat. [[1,2,3], [2,3,4], 5].join(',') will yeild 1,2,3,2,3,4,5
@Xufox yes won't work if there is a comma in the exercise
Xufox raises a valid test case where the join/split fails. We might use spread syntax (...) but it's still unnecessarily more complex than using Object#values and Array#reduce.
That last approach is actually really elegant.
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