How make 3d text in three js
You need to load a font file using a pattern like so:
var loader = new THREE.FontLoader();
loader.load( 'fonts/helvetiker_regular.typeface.json', function ( font ) {
// your code here
} );
See, for example, this three.js example:
https://threejs.org/examples/webgl_geometry_text.html
Also, I'd advise against assigning the same variable name to both your geometry and your mesh.
three.js r.128
I also wrote this tutorial on creating a 3d font, since I hit a few gotchas that I thought were worth documenting.