请问 es6 有什么漂亮的方式实现默认值

[lolizeppelin]

const propsDefault = {
  open: false,
  payload: {
    title: '默认提交',
    styles: stylesDefault,
    data: '默认显示内容',
    onSubmit: null,
    diableSubmit: false,
    onCancel: null,
    diableCancel: false,
  },
};


function defaultProps(payload) {
  const formatedProps = {};
  if (payload.onSubmit === undefined) { formatedProps.onSubmit = propsDefault.payload.onSubmit; } else { formatedProps.onSubmit = payload.onSubmit; }
  if (payload.diableSubmit === undefined) { formatedProps.diableSubmit = propsDefault.payload.diableSubmit; } else { formatedProps.diableSubmit = payload.diableSubmit; }
  if (payload.onCancel === undefined) { formatedProps.onCancel = propsDefault.payload.onCancel; } else { formatedProps.onCancel = payload.onCancel; }
  if (payload.diableCancel === undefined) { formatedProps.diableCancel = propsDefault.payload.diableCancel; } else { formatedProps.diableCancel = payload.diableCancel; }
  if (payload.title === undefined) { formatedProps.title = propsDefault.payload.title; } else { formatedProps.title = payload.title; }
  if (payload.styles === undefined) { formatedProps.styles = propsDefault.payload.styles; } else { formatedProps.styles = payload.styles; }
  if (payload.data === undefined) { formatedProps.data = propsDefault.payload.data; } else { formatedProps.data = payload.data; }
  return formatedProps;
}

这写法太难看了 ES6 有什么好看的写法？

[ZIrong]

```
const defaultProps = (payload) => {
const formatedProps = {};
formatedProps.onSubmit = payload.onSubmit || propsDefault.payload.onSubmit
}
```

[brickyang]

短路赋值

https://segmentfault.com/q/1010000004265392

[brickyang]

具体楼主这个场景，更适合 Object.assign({}, ...defaultProps, payload)

这个方法，payload 里如果有对应的属性，即使是 null 或空值也会覆盖到新对象中。

短路赋值的问题是，如果 payload 中存在的属性是 null 或空值，都会使用 default 中的值。

[lolizeppelin]

谢谢 3 楼 就是这个

[lolizeppelin]

3 楼的方式不行 orz 丢属性 1 楼的可以 orz

[lrz0lrz]

https://babeljs.io/docs/plugins/transform-es2015-parameters/

const f=(a=1)=>a*2

[lrz0lrz]

呃，理解错误，抱歉
{...defaultProps, ...propsDefault.payload}
这样就行了

[lolizeppelin]

握草 楼上这个方法好

[sunnygaofan]

@brickyang 谢谢，纠结这个问题很久了