Reactjs create multiple object array declaration

Question

Below is my coding when I am trying to get the coordinates of the polygon from react-google-maps:

const coords = { lat:{}, lng:{} }

 getCoordinates: () => (polygon) => {
  const paths = polygon.getPath()
  const coor = paths.b

  {coor.map(function(coor, i){
    coords.lat= coor.lat()
    coords.lng= coor.lng()
  })}
  return console.log(coords)
}

I'm trying to get the object array for "coords"like below:

coords = [
  { lat: 3.1323583333745533, lng: 101.62676453590393 },
  { lat: 3.1318226928949433, lng: 101.62672162055969 },
  { lat: 3.131753059612469, lng: 101.6274243593216 }
]

But using the code will give me this:

coords = { 
  lat: 3.131753059612469, 
  lng: 101.6274243593216 
}

which is the last coordinates out of the three.

How do I can get all three coordinates under "coords"?

AngYC · Accepted Answer · 2017-11-06 03:53:40Z

2

You have to push to an array instead of object, hope it helps!

let coords = [];

getCoordinates: () => (polygon) => {
    const paths = polygon.getPath();
    const coor  = paths.b;

    coor.forEach((c) => {
        coords.push({
            lat: c.lat(),
            lng: c.lng()
        });
    });

    return console.log(coords);
}

edited Nov 6, 2017 at 3:53

answered Nov 6, 2017 at 3:35

AngYC

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5 Comments

Bergi Over a year ago

Don't use map together with push. If you want to push to an array explicitly, use a normal for (let c of coor) loop instead

AngYC Over a year ago

Sorry for using the wrong method, I am just modifying the code without checking the function used, updated the code to forEach instead

Bergi Over a year ago

Thanks, better, though I still dislike the forEach + push combination when one could just use map :-P

AngYC Over a year ago

Got it, I am overusing forEach recently so can't think of using map, will try to use more map and filter etc in the future =)

Bergi Over a year ago

I recommend to never use forEach. For side effects (i.e. when you don't need a result value), use for … of. This also allows to use things like yield, await, return, break and continue in the loop body.

Bergi · Accepted Answer · 2017-11-06 03:37:35Z

2

This code is really confused. You seem to be looking for

function getCoordinates(polygon) {
  const paths = polygon.getPath()
  const coords = paths.b.map(coor => ({
    lat: coor.lat(),
    lng: coor.lng()
  }));
  return coords;
}

console.log(getCoordinates(…));

answered Nov 6, 2017 at 3:37

Bergi

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