obj means plain javascript object such as { Xx: 1, Xy: 0, Yx: 0, Yy: 1, Tx: 0, Ty: 0 }

cls1 is for a class with field declarations without default value

class XfCls1 {
    Xx;
    Xy;
    Yx;
    Yy;
    Tx;
    Ty;
    constructor(Xx, Xy, Yx, Yy, Tx, Ty) {
        this.Xx = Xx;
        this.Xy = Xy;
        this.Yx = Yx;
        this.Yy = Yy;
        this.Tx = Tx;
        this.Ty = Ty;
    }
}

cls2 is for a class without field declarations such as

class XfCls2 {
    constructor(Xx, Xy, Yx, Yy, Tx, Ty) {
        this.Xx = Xx;
        this.Xy = Xy;
        this.Yx = Yx;
        this.Yy = Yy;
        this.Tx = Tx;
        this.Ty = Ty;
    }
}

cls3 is for a class with field declarations and with default values

class XfCls3 {
    Xx = -0;
    Xy = -0;
    Yx = -0;
    Yy = -0;
    Tx = -0;
    Ty = -0;
    constructor(Xx, Xy, Yx, Yy, Tx, Ty) {
        this.Xx = Xx;
        this.Xy = Xy;
        this.Yx = Yx;
        this.Yy = Yy;
        this.Tx = Tx;
        this.Ty = Ty;
    }
}

arr1 stands for a number array of length 6 such as [1, 0, 0, 1, 0, 0]. In this case V8 chooses to use PACKED_SMI_ELEMENTS or PACKED_DOUBLE_ELEMENTS

arr2 stands for a number array of length 6 in which all the values are forced to be float64 at creation time (PACKED_DOUBLE_ELEMENTS) [-0 + 1, -0, -0, -0 + 1, -0, -0]

arr3/arr4 are the same as arr1/arr2 but instead of using array destructuring to access its elements (const [ Xx, Xy, Yx, Yy, Tx, Ty ] = arr), we acces them one by one using the index : const Xx = arr[0], const Xy = arr[1], ...

By default the operation performed on the Xfs reads the values of 2 Xfs and write in the 3rd Xf. It is a read and write (rw) operation. To compare performance when only read operations are made on the xf, the option ro can be added as a second argument.

node xf6.js obj rw or node xf6.js obj ro or node xf6.js cls1 rw or node xf6.js cls1 ro...

yarn run-all

node --cpu-prof --cpu-prof-name cls1_rw.cpuprofile xf6.js cls1 rw and open it with Chrome Dev Tools