The zoom level in javascript is set by the tile levels of the first map loaded. Once you hit the max level, you cannot zoom in further.
You have two options. Publish/use your own basemap with additional levels, and ensure that basemap is loaded FIRST
or
Create you map object with a custom set of LODs (levels of detail) specifying more levels.
We do the later, since our basemap as 0-20 levels (we will be adding level 21 and 22 soon, 20 is 1:564, 21 1:282, 22 1:141) and load the custom LODs to override the zoom scales.
this.map = new Map("map",
{ infoWindow: popup,
basemap: "streets",
autoResize: true,
sliderStyle: style,
logo: false,
showAttribution: false,
lods: lods,
minZoom:10 });
with lods
var lods =
[
{
"level": 0,
"resolution": 156543.03392800014,
"scale": 5.91657527591555E8
},
{
"level": 1,
"resolution": 78271.51696399994,
"scale": 2.95828763795777E8
},
{
"level": 2,
"resolution": 39135.75848200009,
"scale": 1.47914381897889E8
},
{
"level": 3,
"resolution": 19567.87924099992,
"scale": 7.3957190948944E7
},
{
"level": 4,
"resolution": 9783.93962049996,
"scale": 3.6978595474472E7
},
{
"level": 5,
"resolution": 4891.96981024998,
"scale": 1.8489297737236E7
},
{
"level": 6,
"resolution": 2445.98490512499,
"scale": 9244648.868618
},
{
"level": 7,
"resolution": 1222.992452562495,
"scale": 4622324.434309
},
{
"level": 8,
"resolution": 611.4962262813797,
"scale": 2311162.217155
},
{
"level": 9,
"resolution": 305.74811314055756,
"scale": 1155581.108577
},
{
"level": 10,
"resolution": 152.87405657041106,
"scale": 577790.554289
},
{
"level": 11,
"resolution": 76.43702828507324,
"scale": 288895.277144
},
{
"level": 12,
"resolution": 38.21851414253662,
"scale": 144447.638572
},
{
"level": 13,
"resolution": 19.10925707126831,
"scale": 72223.819286
},
{
"level": 14,
"resolution": 9.554628535634155,
"scale": 36111.909643
},
{
"level": 15,
"resolution": 4.77731426794937,
"scale": 18055.954822
},
{
"level": 16,
"resolution": 2.388657133974685,
"scale": 9027.977411
},
{
"level": 17,
"resolution": 1.1943285668550503,
"scale": 4513.988705
},
{
"level": 18,
"resolution": 0.5971642835598172,
"scale": 2256.994353
},
{
"level": 19,
"resolution": 0.29858214164761665,
"scale": 1128.497176
},
{
"level": 20,
"resolution": 0.14929107082380833,
"scale": 564.248588
}
];