javascript - JS - Promise + geolocation.watchPosition -

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i'm trying use javascript promise geolocation, can't make work correctly geolocation.watchposition, then clause being called once :

function geolocation() {   this._options = {     enablehighaccuracy: true,      maximumage        : 10000,      timeout           : 7000   } }  geolocation.prototype = {   watchid() { return this._watchid; },   set watchid(watchid) { this._watchid = watchid; },   options() { return this._options; },   // hascapability: function() { return "geolocation" in navigator; },   _promise: function(promise) {     var geolocation = this;     if (promise == "getposition")       return new promise(function(ok, err) {         navigator.geolocation.getcurrentposition(           ok.bind(geolocation), err.bind(geolocation),           geolocation.options         );       });     else if (promise == "watchposition")       return new promise(function(ok, err) {         geolocation.watchid = navigator.geolocation.watchposition(           ok.bind(geolocation), err.bind(geolocation),           geolocation.options         );       });   },   getposition: function() { return this._promise('getposition'); },   watchposition: function() {     this.clearwatch();     return this._promise('watchposition');   },   clearwatch: function() {     if (!this.watchid) return;     navigator.geolocation.clearwatch(this.watchid);     this.watchid = null;   } };  var geolocation = new geolocation(); geolocation.watchposition()   .then(     function(position) {       console.log("latitude: " + position.coords.latitude + " - longitude: " + position.coords.longitude)     },     function(error) {       console.log("error: " + error);     }   )

i tried intermediary promise returned watchposition/0, returns same result.

what missing ?

answering myself.

following @benjamin gruenbaum advice on using callback, it's possible combine single callback handling both geolocation.watchposition responses promise, , use then().catch() pattern (below in notify function) :

function geolocation() {   this._options = {     enablehighaccuracy: true,      maximumage        : 10000,     timeout           : 7000   } };  geolocation.prototype = {   watchid() { return this._watchid; },   set watchid(watchid) { this._watchid = watchid; },   options() { return this._options; },   // hascapability: function() { return "geolocation" in navigator; },   _promise: function(promise, cb) {     var geolocation = this;     return new promise(function(ok, err) {       if (promise == "getposition")         navigator.geolocation.getcurrentposition(cb, cb,           geolocation.options         );       else if (promise == "watchposition")         geolocation.watchid = navigator.geolocation.watchposition(           cb, cb, geolocation.options         );     });   },   getposition: function(cb) { return this._promise("getposition", cb); },   watchposition: function(cb) {     this.clearwatch();     return this._promise("watchposition", cb);   },   clearwatch: function() {     if (!this.watchid) return;     navigator.geolocation.clearwatch(this.watchid);     this.watchid = null;   } };  /* testing functions module */ function log(data) { console.log(date() + " " + data); }; function logok({coords: {latitude: latitude, longitude: longitude}}) {   log("latitude: " + latitude + " - longitude: " + longitude); }; function logerror({code: code, message: message}) {   log("error geo " + code + " - " + message); };  /* callback module */ function notify(event) {   return new promise(       function(ok, err) { event.coords ? ok(event) : err(event); }     ).then(logok).catch(logerror); };  /**/ var geolocation = new geolocation(); // geolocation.getposition(notify); geolocation.watchposition(notify);

not sure if use promise correctly, works , allows take advantage of chaining.


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