How to Concatenate Arrays of Objects and return single Array of Arrays?

Question

I recieve 4 arrays from Geoserver. Each of these arrays contain objects holding lat lng data as here geoserver response . I need to merge these 4 arrays in one single Array and then convert objects inside them into arrays. This was used to structure some other response from another API:

var routes = e.routes[0].coordinates
     var coords = routes.map(function(obj){
              return Object.keys(obj).sort().map(function(key){
                            return obj[key];
                        })
                    })

This is routes and this is coords and coords is expected result for Geoserver response. I get my geoserver response . structured as shown in image after I did this:

function goPark(routeLayer){ 
    var finalRoute = routeLayer._layers;
    var coordsArray = Object.keys(finalRoute).map(key => {
        return finalRoute[key]
    });
    coordsArray.forEach(function(data){
        var xy = data._latlngs;
    }) 

If i proceed with code below I recieve arrays structured as I want, see here , but still separated. I need to merge them somehow in one single array!

 var xxy = xy.map(function(obj){
        return Object.keys(obj).map(function(key){
            return obj[key];
        })
    })

Answer 1

There is a great npm package for this kinda task that i used once called deepmerge You can use it to merge one or more arrays or objects into one and control the enumerable properties.

Answer 2

If you need lazy loading of values only when you access it, you can turn the accumulator function into a generator (for performance). There's other things you can do like using promises and a generator to yield values. Though if you aren't seeing any performance issues it's unnecessary.

function accGoPark(reset) {
   return accFn(goPark, reset);
}

function accFn(fn, reset) {
   const accs = accFn.accs = accFn.accs || {};
   const { name } = fn;
   accs[name] = !accs[name] || reset ? [] : accs[name];
   accs[name] = accs[name].concat( fn() );
   return accs[name];
}

You are just setting a variable xy to a reference to your last data._latlngs iterated in your forEach loop, which is why you only get the last one. You should just map coordsArray directly.

xxy = coordsArray.map(function(data){
    var obj = data._latlngs;
    return Object.keys(obj).map(function(key){
        return obj[key];
    })
})

Using Object.values, destructuring, and arrow functions to simplify syntax:

xxy = routeLayer.map( ({ _layers: { _latlngs: xy })  => Object.values(xy) );