函數式編程和局部功能狀態分配

Question

我最近轉換代碼是什麼，我認爲是部分至少，功能的JavaScript。 這是一個網頁表單驗證過程。在過程的每一步中，函數都會執行它們自己的驗證層，並在將數據傳遞給下一個函數之前對其進行修改。

1）我的第一個問題是......可以下面的代碼被認爲至少「部分」的功能？

你會發現，在使用requiredfields我創建了兩個任務...狀態。他們是當地的功能，並且該功能不具有外部的副作用....

2）就是這種當地assignement不好的做法，在功能的編程範式的背景下？這是否被認爲是「局部副作用」？

這裏是模型：

function linkmodel() { 
    return { 
     title: { 
      content: undefined, 
      validation: { 
       type: "string", 
       required: true, 
       minLength: 1, 
       maxLength: 3, 
       validationErrorMessage: "Your title must be a valid string between 1 and 35 characters" 
      } 
     }, 

     email: { 
      content: undefined, 
      validation: { 
       type: "email", 
       required: true, 
       minLength: 1, 
       maxLength: 60, 
       validationErrorMessage: "Your email must be between 1 and 50 characters" 
      } 
     }, 


     link: { 
      content: undefined, 
      validation: { 
       type: "url", 
       required: true, 
       minLength: 1, 
       maxLength: 500, 
       validationErrorMessage: "Your link name must be a valid email between 1 and 50 characters" 
      } 
     }, 

     description: { 
      content: undefined 
     } 
    } 
} 


export default linkmodel 

這裏是驗證系統：

app.post("/", function(req, res) { 
    let form = new forms.IncomingForm() 

    form.parse(req, function(err, fields, files) { 

    // Lodash launching the function flow 
    let errorMessageBag = _.flow(objectWithFieldsToValidate, 
            requiredFields, 
            stringLengthValidationCheck, 
            emailValidation) 

    let result = errorMessageBag(fields, linkmodel()) // That's the end result 
    console.log("result", result) 
    }) 



    // Return object containing all fields to validate and their criterias 
    function objectWithFieldsToValidate(fields, model) { 
    // Remove all model fields that have no validation criteria in model. Description is one of those. 
    let modelFieldsToValidate = _.pickBy(model, function(value, key) { return value.validation !== undefined }) 

    // Remove from form field any entry that doesn't have a corresponding key in model 
    let formFieldsToValidate = _.pick(fields, Object.keys(modelFieldsToValidate)) 
    _.forOwn(modelFieldsToValidate, function(value1, key1) { 
     _.forOwn(formFieldsToValidate, function(value, key) { 
     if (key1 === key) { 
      modelFieldsToValidate[ key ].content = value 
     } 

     }) 
    }) 
    return modelFieldsToValidate 
    } 

    // Take care of required fields 
    function requiredFields(objectWithFieldsToValidate) { 
    let okField = {} 
    let errors = {} 

    // error: field required but empty: add it to errors literal object 
    _.forOwn(objectWithFieldsToValidate, function(value, key) { 
     if (objectWithFieldsToValidate[ key ].validation.required === true && objectWithFieldsToValidate[ key ].content === "") { 
     errors[ key ] = objectWithFieldsToValidate[ key ].validation.validationErrorMessage 
     } else { 
     // no error: add field to litteral okField 
     okField[ key ] = value 

     } 
    }) 
    return ({ "okField": okField, "errors": errors }) 
    } 


    function stringLengthValidationCheck(requiredFields) { 
    let validatedFields = requiredFields 
    _.forOwn(validatedFields.okField, function(value, key) { 
     // Error: field length is not valid 
     if (!validator.isLength(value[ "content" ], 
     { min: value[ "validation" ].minLength, max: value[ "validation" ].maxLength } 
    )) { 
     // Add error message to errors errors literal object 
     validatedFields[ "errors" ][ key ] = value[ "validation" ].validationErrorMessage 
     // Remove problematic field from okFields 
     delete validatedFields[ "okField" ][ key ] 
     } 
    }) 

    return validatedFields 
    } 


    function emailValidation(stringLengthValidationCheck) { 
    let validatedFields = stringLengthValidationCheck 
    _.forOwn(validatedFields.okField, function(value, key) { 
     // Error 
     if (value["validation"]["type"] === "email" && !validator.isEmail(value[ "content" ])) { 
     // Add error message to errors 
     validatedFields[ "errors" ][ key ] = value[ "validation" ].validationErrorMessage 
     // Remove problematic field from okFields 
     delete validatedFields[ "okField" ][ key ] 
     } 
    }) 

    return validatedFields 
    } 

3）如果你看到的方式來改善這個代碼，我將不勝感激，看看有什麼更好的功能重構你可以想出，仍然使用lodash。

Answer 1

如上一個意見建議，具體的代碼審查可能不會這麼一個話題，但回答你的問題的概述部分：是的，沒有外部可見的副作用的功能，可以在更廣泛的認爲是「功能性」意義---比如「行爲功能」 - 即使它在內部使用任務。

一個可能這裏的問題可能是如何驗證副作用確實是僅供內部使用，不能從外部看到。

另一個理論上有趣的事實是，存在一些行爲功能的功能，但只能使用和（內部）分配。有關更多詳細信息，請參閱the paper（如果您無法訪問ACM數字圖書館中的論文，請嘗試在Web上搜索論文的標題和/或作者）。