Google Maps API: Draw a route using points of a polyline

Question

I'm using google directions to get the main route between two points and it's alternatives (3) so each alternative contains steps and also the overview polyline resultant of all that steps so I want to draw those 3 polylines in a map to see the the main route and the alternatives, do you know how to do that?

This is one of the overview polylines

"overview_polyline": {
    "points": "uiyqBfb~zQgGwAgCtM}DfVpDrBeBbFqDjFmHfXkOzh@cKxNuGlW_BzSiJxZcBfHuS~NqK`Ia@lFgIpC{fAoDcW~BmEbBeqAmIaEoBgB{KB}J}OoJcBwAeHuAwDaBkCnCwKjLcNgBkIc@oDtD}EhG{GjAgVcDsN{Bm@|FaAvOiE|Va`@xw@}Jh]dPhcArEzQuIpXkMna@sDbPb@fGdDxE|O~E~ZzH`ThQtdA|jA|NfRxC~Jc@p[iEd`@WbSvKza@rTlf@~ArMfFtJrChOjQfM~JzX@~VnOn]g@jMcBdLkGzHg@|DyGfEcEjLgEvHaKoAgNiEoLsCoKUkUz@_CtBqI?eDhAeGeDsIRyK`IqIfIkPtEuUbNcLpOuPpZ]rHpHtQpLnOlEvIEpJfId[pShc@z@th@cLx@yNnGk`@rVsLfLm|@v|@_VxKgZ`XmR~VeH~^~@jIsAvLeD~LiCre@mGhP}Eda@D`YqBt[aIna@iI|Db@pENpDtAzCc@pG{@bFuQlGcLxGuUz@}PhBUhIcD`Eof@rMwUfEk^|Ck}@tFcMjDiP~GeN`RcF]}CxBmEc@{BvAoGdCsKpFmOgEuB\\eEjKjB~GwGvBiDsDgEyGwD`JeDTgCyGuCOcGvFmGzJeC_DwCa@WvM{@rC_CJuHoIiFEgBwC{HeJuCm@sAxAf@fFoBvBmDx@iNm@mCxD{DkAwMrDcJrF}IhSsDbB{D{AyY_CoK~AuP`@uPm@eKbC}Lq@eNsCeDeC_Jj@wIb@mEr@eHgBiGoKiGyJeDgI}CmHG{KiCyO}P}IgNkNaUoKkCkDYiB{Bg@sFwAaDeDsSwT}PY{KaEeIBqTfEiEeEgDkLyUyIkT}BoP{DyGiGwHiW{Is^kOiScLmTeIqGsPcTqD_FgMaDwNqMwOuVqHy\\yFkMmGwEaHeAqBmCr@aU_CiBoSpDyHBkH}Kc[kTq[mPyYiOyVyR_Sc\\{ZsRwfA{]wh@oPaNVyIiFeHKmE~AqAhEwNgDiNmFgL~H}Cs@oIxH{DRsFqG_FoA}GfEgP~MuFi@}Sh@yDdDgInBaGh@w[cCwH~AeGeFeLcUD_LkAiDwUaJuMXaQuGyBgB|LkLhL{JnPoGhIuQfACz@kEqCgBF}F~@qL{AaHa@qJCcHiAsBeH]{PiHeJoCu@{BxCwC[cFiVePaGt@}KoH_NyMyNiGyWwMeIgFiLmIod@lEoSaf@eIrF{@oG}C_@{B{CsEmAmDgCcAoL_AaFs@oCl@mD\\eMkHkFaJqFkEiPN}HrBvKdEzExA|FJJ"
  },

Answer 1

Use the decodePath function of the geometry library to decode the encoded points to use as the path of a Polyline.

  var polyline = new google.maps.Polyline({
    path: google.maps.geometry.encoding.decodePath(json.overview_polyline.points),
    map: map
  });

proof of concept fiddle

code snippet:

var json = {
  "overview_polyline": {
    "points": "uiyqBfb~zQgGwAgCtM}DfVpDrBeBbFqDjFmHfXkOzh@cKxNuGlW_BzSiJxZcBfHuS~NqK`Ia@lFgIpC{fAoDcW~BmEbBeqAmIaEoBgB{KB}J}OoJcBwAeHuAwDaBkCnCwKjLcNgBkIc@oDtD}EhG{GjAgVcDsN{Bm@|FaAvOiE|Va`@xw@}Jh]dPhcArEzQuIpXkMna@sDbPb@fGdDxE|O~E~ZzH`ThQtdA|jA|NfRxC~Jc@p[iEd`@WbSvKza@rTlf@~ArMfFtJrChOjQfM~JzX@~VnOn]g@jMcBdLkGzHg@|DyGfEcEjLgEvHaKoAgNiEoLsCoKUkUz@_CtBqI?eDhAeGeDsIRyK`IqIfIkPtEuUbNcLpOuPpZ]rHpHtQpLnOlEvIEpJfId[pShc@z@th@cLx@yNnGk`@rVsLfLm|@v|@_VxKgZ`XmR~VeH~^~@jIsAvLeD~LiCre@mGhP}Eda@D`YqBt[aIna@iI|Db@pENpDtAzCc@pG{@bFuQlGcLxGuUz@}PhBUhIcD`Eof@rMwUfEk^|Ck}@tFcMjDiP~GeN`RcF]}CxBmEc@{BvAoGdCsKpFmOgEuB\\eEjKjB~GwGvBiDsDgEyGwD`JeDTgCyGuCOcGvFmGzJeC_DwCa@WvM{@rC_CJuHoIiFEgBwC{HeJuCm@sAxAf@fFoBvBmDx@iNm@mCxD{DkAwMrDcJrF}IhSsDbB{D{AyY_CoK~AuP`@uPm@eKbC}Lq@eNsCeDeC_Jj@wIb@mEr@eHgBiGoKiGyJeDgI}CmHG{KiCyO}P}IgNkNaUoKkCkDYiB{Bg@sFwAaDeDsSwT}PY{KaEeIBqTfEiEeEgDkLyUyIkT}BoP{DyGiGwHiW{Is^kOiScLmTeIqGsPcTqD_FgMaDwNqMwOuVqHy\\yFkMmGwEaHeAqBmCr@aU_CiBoSpDyHBkH}Kc[kTq[mPyYiOyVyR_Sc\\{ZsRwfA{]wh@oPaNVyIiFeHKmE~AqAhEwNgDiNmFgL~H}Cs@oIxH{DRsFqG_FoA}GfEgP~MuFi@}Sh@yDdDgInBaGh@w[cCwH~AeGeFeLcUD_LkAiDwUaJuMXaQuGyBgB|LkLhL{JnPoGhIuQfACz@kEqCgBF}F~@qL{AaHa@qJCcHiAsBeH]{PiHeJoCu@{BxCwC[cFiVePaGt@}KoH_NyMyNiGyWwMeIgFiLmIod@lEoSaf@eIrF{@oG}C_@{B{CsEmAmDgCcAoL_AaFs@oCl@mD\\eMkHkFaJqFkEiPN}HrBvKdEzExA|FJJ"
  }
};

function initialize() {
  var map = new google.maps.Map(
    document.getElementById("map_canvas"), {
      center: new google.maps.LatLng(37.4419, -122.1419),
      zoom: 13,
      mapTypeId: google.maps.MapTypeId.ROADMAP
    });
  var polyline = new google.maps.Polyline({
    path: google.maps.geometry.encoding.decodePath(json.overview_polyline.points),
    map: map
  });
  var bounds = new google.maps.LatLngBounds();
  for (var i = 0; i < polyline.getPath().getLength(); i++) {
    bounds.extend(polyline.getPath().getAt(i));
  }
  map.fitBounds(bounds);
}
google.maps.event.addDomListener(window, "load", initialize);

html,
body,
#map_canvas {
  height: 100%;
  width: 100%;
  margin: 0px;
  padding: 0px
}

<script src="https://maps.googleapis.com/maps/api/js?libraries=geometry&key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk"></script>
<div id="map_canvas"></div>