Euler to Quaternion in JavaScript, designed for Snapchat Lens Studio

eulerToQuaternion.js

global.eulerToQuaternion = function (heading, attitude, bank) {
    var c1 = Math.cos(heading / 2)
    var c2 = Math.cos(attitude / 2)
    var c3 = Math.cos(bank / 2)
    var s1 = Math.sin(heading / 2)
    var s2 = Math.sin(attitude / 2)
    var s3 = Math.sin(bank / 2)
    return new quat(
        c1 * c2 * c3 - s1 * s2 * s3,
        s1 * s2 * c3 + c1 * c2 * s3,
        s1 * c2 * c3 + c1 * s2 * s3,
        c1 * s2 * c3 - s1 * c2 * s3
    );
}