我正在学习javascript,并且在尝试在解构时为变量提供默认值时陷入了ES6语法的困境。基本上,我试图分配一个给定变量的对象的属性值,如果该值为false / null / undefined,我希望它是一个空对象。例如,
let foo = { prop1: 'hello!', prop2: null } const prop1 = foo.prop1 || {} const prop2 = foo.prop2 || {} console.log(prop1) // hello! console.log(prop2) // {}
want这就是我想要的,👇是我认为与上述等效的ES6糖语法(在这里不起作用。)
let foo = { prop1: 'hello!', prop2: null } const { prop1 = {} } = foo const { prop2 = {} } = foo console.log(prop1) // hello! console.log(prop2) // null
但是以某种方式,有时它似乎可以在React中工作,但有时却不能..是兼容性问题吗?太混乱了!
您可能对null和undefined之间的区别感到困惑,例如:
const { dogName = 'snickers' } = { dogName: undefined } console.log(dogName) // what will it be? 'snickers'! const { dogName = 'snickers' } = { dogName: null } console.log(dogName) // what will it be? null! const { dogName = 'snickers' } = { dogName: false } console.log(dogName) // what will it be? false! const { dogName = 'snickers' } = { dogName: 0 } console.log(dogName) // what will it be? 0!
摘自:http : //wesbos.com/destructuring-default-values/