JS解决Cannot set properties of undefined错误的几种方法

const value = undefined
value.a  // TypeError: Cannot read properties of undefined (reading 'a')
value[0]  // TypeError: Cannot read properties of undefined (reading '0')

const value = {}
value.a.b // TypeError: Cannot read properties of undefined (reading 'b')
value.a  // undefined

const value = undefined
//解决方法1： if条件
if（value）{
  value = {}
	value.a
}
// 解决方法2：?运算符
value?.a
// 解决方法3：||运算符
const preValue = value || {}
preValue.a