vue element-ui 日期选择器el-date-picker设置开始日期和结束日期的选择区间

<el-form-item label="项目开始日：" prop="F_StartDate" :rules="{ required: false, message: '请输入项目开始日', trigger: 'blur' }">
                                <el-date-picker v-model="form.F_StartDate"
                                                type="date"
                                                size="small"
                                                placeholder="选择项目开始日"
                                                value-format="yyyy-MM-dd"
                                                 :picker-options="pickerBeginDateBefore"
                                                >
                                </el-date-picker>
                            </el-form-item>

<el-form-item label="项目截止日：" prop="F_EndDate" :rules="{ required: false, message: '请输入项目截止日', trigger: 'blur' }">
                                <el-date-picker v-model="form.F_EndDate"
                                                type="date"
                                                size="small"
                                                placeholder="选择项目截止日"
                                                value-format="yyyy-MM-dd"
                                                 :picker-options="pickerBeginDateAfter"
                                                >
                                </el-date-picker>
                            </el-form-item>

data: {
        pickerBeginDateBefore: {
            disabledDate: time => {
                let endDate = vm.form.F_EndDate;
                let beginDateVal = new Date(endDate);
                if (endDate) {
                    return time.getTime() > beginDateVal;
                }
            }
        },
        pickerBeginDateAfter: {
            disabledDate: time => {
                let startDate = vm.form.F_StartDate;
                let beginDateVal = new Date(startDate);
                if (startDate) {
                    return time.getTime() < beginDateVal - 3600 * 1000 * 24 * 1;
                }
            }
        },
}