setComponent( index, value ) {

		switch ( index ) {

			case 0: this.x = value; break;
			case 1: this.y = value; break;
			case 2: this.z = value; break;
			case 3: this.w = value; break;
			default: throw new Error( 'index is out of range: ' + index );

		}

		return this;

	}
Allows to set a vector component with an index.

@param {number} index - The component index. `0` equals to x, `1` equals to y,
`2` equals to z, `3` equals to w.
@param {number} value - The value to set.
@return {Vector4} A reference to this vector.