Use reduce to remove object in an array

Question

I am trying to return an array that contain of one of property. So there is an array of objects like

[{x: 5, y: 607, width: 782, height: 602, line_width: 3, …},
 {x: 10, y: 602, width: 772, height: 592, line_width: 3, …},
 {x: 0, y: 400, size: 18, text: 'This cer..}, ..]

Some object has section: 'TextInstruction' property defined and some do not.

I am trying to return an array that is only containing section with no duplicate and no undefined.

So return ['TextInstruction', 'RectangleInstruction', ...]
No [undefined, 'TextInstruction', 'TextInstruction', ...]

Can anyone help me with JavaScript to get this using reduce() function?

Why do you want to use reduce? Seems like you want to filter the objects that do not have a section key. Also, the intended result is unclear; it looks like what you want is an array of the unique values of the section key, which you could do easily with the answers to From an array of objects, extract value of a property as array and Get all non-unique values (i.e.: duplicate/more than one occurrence) in an array — Heretic Monkey
– Heretic Monkey, Commented Oct 7, 2022 at 17:34

Clem · Accepted Answer · 2022-10-07 17:04:34Z

0

You don't need reduce to do that. You can do it with filter and map.

myArray
  // filter missing sections
  .filter(a => a.section)
  // map to array of sections
  .map(a => a.section)
  // filter unique
  .filter((a, i, arr) => arr.indexOf(a) === i)

answered Oct 7, 2022 at 17:04

Clem

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Carsten Massmann · Accepted Answer · 2022-10-07 17:30:12Z

0

The reduce() way of doing it could be something like this:

const data=[{a:12,b:45,section:"first"},{section:"second",d:5,f:7},{x:23,y:78,height:200},{a:445,x:34,section:"first"}];

const res1=Object.keys(data.reduce((a,c)=>{
  if(c.section) a[c.section]=1;
  return a;
 }, {}));

// Or, using the es6 Set object:
const res2=[...data.reduce((a,c)=>{
  if(c.section) a.add(c.section);
  return a;
 }, new Set())];

// show results:
console.log(res1,res2);

The second approach makes sense when the values to be collected are objects (and not only strings).

edited Oct 7, 2022 at 17:30

answered Oct 7, 2022 at 17:13

Carsten Massmann

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Hamid Raza · Accepted Answer · 2022-10-07 17:36:03Z

0

You can try this:

var objectArray = {someting....}; // Your Object Array
var indexOfObject = objectArray.findIndex(object => {
    return object.section == null;
});
objectArray.splice(indexOfObject, 1);

answered Oct 7, 2022 at 17:36

Hamid Raza

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