Use reduce to remove object in an array-CodePudding

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?

CodePudding user response：

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)

CodePudding user response：

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).

CodePudding user response：

You can try this:

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