It is suggested to use a standardized attribute naming convention in html, of all lower case with words separated by dashes. This can be seen in Bootstrap as an example:
"col-md-12", "btn-default", "my-form", "menu-bar"
Use this naming convention for attributes, classes, and ids.
var col-md-12 = 3; //doesn't work because it of dashes
Angular uses camel casing:
colMd12 btnDefault myForm menuBar