TypeError: Cannot read properties of null (reading ‘indexOf‘)

问题原因：TypeError:无法读取null的属性（读取’indexOf’），所以在使用indexOf()之前，先判断使用indexOf()的变量是否为null。

我下面举得例子就是因为没有读到this.employeeData.workTime的值，是个null，所以才报这个错的！！！

报错如下图：

原来代码如下：

   var workTime = "";        
            if (this.employeeData.workTime.indexOf("-") > -1) {
              var workTimeArray = this.employeeData.workTime.split("-");
              workTime =
                workTimeArray[0] +
                "年" +
                workTimeArray[1] +
                "月" +
                workTimeArray[2] +
                "日";
            }

修改后代码如下：

 var workTime = "";   
            if(this.employeeData.workTime!=null){
            if (this.employeeData.workTime.indexOf("-") > -1) {
              var workTimeArray = this.employeeData.workTime.split("-");
              workTime =
                workTimeArray[0] +
                "年" +
                workTimeArray[1] +
                "月" +
                workTimeArray[2] +
                "日";
            }    
            }  

问题就迎刃而解喽~~~