使用外部范围的部分参数调用 javascript 对象方法

Question

我有一个 getValidators 函数，它返回一个带有验证器方法的对象：

export function getValidators()  {

  return {
    required: (node, value, [mark='', falsy=[undefined, '']]) => {
      const notValid = falsy.includes(value);
      return setNotValid(node, notValid, mark);
    },
    // ... other validator functions ...
  };
};

所有验证器函数都有三个参数：节点、值和数组：args

我可以运行验证器功能：

let validator = 'required';
let validators = getValidators()
let result = validators[validator](node, value, args);

但我喜欢使用来自某个外部范围的参数节点和值来运行下面修改后的验证器函数：

export function getValidators()  {

  return {
    required: ([mark='', falsy=[undefined, '']]) => {
      const notValid = falsy.includes(value);
      return setNotValid(node, notValid, mark);
    },
    // ...
  };
};

并喜欢如下图运行：

// ... node and value args passed in from outer scope ...?
let result = validators[validator](args);

更新：我不能使用getValidators(node, value)，因为会首先调用 getValidators 来添加额外的验证器函数。

let validators = getValidators();
validators[method] = aValidatorFunc;
.....
.....
function runValidators() {
  .....
  // use the updated validators instance to run the validators
  for (let validator of .....) { 
     // node and value will change in this loop as well
     ... 
     let result = validators[validator](args);
  }
  ...
}

Answer 1

找到了一种使用bind(this)的解决方案：

let validators = getValidators();
validators[method] = aValidatorFunc;
.....
.....
function runValidators() {
  .....
  // use the updated validators instance to run the validators
  for (let validator of .....) { 
     // node and value will change in this loop as well
     ...
     const validatorFunc = validators[validator].bind({node, value})  // bind this
     // or with call with a given this as firtst argument: 
     // const validatorFunc = validators[validator].call({node, value}, args); 

     let result = validatorFunc(args);
  }
  ...
}

绑定我们不能使用箭头函数，所以要使用'this'：

export function getValidators()  {

  return {
    required: function([mark='', falsy=[undefined, '']]) {  // function
      const notValid = falsy.includes(this.value);
      return setNotValid(this.node, notValid, mark);
    },
    // ...
  };
};

Answer 2

不知道这是否是您的意思，但您可以像这样从外部函数的范围内传递它们：

export function getValidators(node, value)  { // Put them in the argument list here
  return {
    required: ([mark='', falsy=[undefined, '']]) => {
      const notValid = falsy.includes(value);
      return setNotValid(node, notValid, mark);
    },
    //...
  };
};

let validator = 'required';
let validators = getValidators(node, value); // Pass your node and value to the outer function

// Now call it like you wanted to call it:
let result = validators[validator](args);