说明

this.canvasFab.on("mouse:up", (e) => {
    console.log(e.target) // 动画没完成时，框选中的元素，这里会返回null
    const selectObjects = this.canvasFab.getActiveObjects() // 调用该方法才能获取框选的元素
    console.log("selectObjects:",selectObjects)

});