JAVASCRIPT：将json键名作为参数传入，通过参数获取值

Question

在 javascript 中，有没有办法将 JSON 键名视为变量？

例如，下面我想每次对 JSON 中不同键的值执行（任何一组操作），通过将键名作为参数提供给 function 来告诉它要获取哪个 json 键。

这里的基本思想是：使 function 做 (x) 无论它给出什么 JSON。 我只需要告诉它我想要什么钥匙。

var myObj = {name: "John", age: 31}; // dataset #1
var myObj2 = {month: "January", day: 20}; //dataset #2

function myFunction(jsonName, variableKeyName) {   

  var variableKeyValue = jsonName + "." + variableKeyName;  //wrong way to do this, apparently.
 
  console.log(variableKeyValue); 
}

myFunction("myObj", "name"); //want this to log "John", not the string "myObj.name".
myFunction("myObj2", "day"); //want this to log "20", not the string "myObj2.day". 

这可能吗？ 如何让 function 分配我正在使用参数构建的字符串的值，而不仅仅是字符串“jsonNameX.variableKeyNameX”？

Answer 1

const myObj = {name: "John", age: 31}; // dataset #1
const myObj2 = {month: "January", day: 20}; //dataset #2

function myFunction(json, variableKeyName) {   
  const variableKeyValue = json[variableKeyName]; 
  console.log(variableKeyValue); 
}

myFunction(myObj, "name"); // this log "John"
myFunction(myObj2, "day"); // this log 20 

或者您可以使用“this”关键字和变量名（而不是变量标识符 == 引用）访问全局上下文

const myObj = {name: "John", age: 31}; // dataset #1
const myObj2 = {month: "January", day: 20}; //dataset #2

function myFunction(jsonName, variableKeyName) {   
  const variableKeyValue = this[jsonName][variableKeyName]; 
  console.log(variableKeyValue); 
}

myFunction("myObj", "name"); // this log "John"
myFunction("myObj2", "day"); // this log 20 

Answer 2

是的，你可以做到。 您可以像这样获得 JSON 值：

jsonName.variableKeyName;

但你也可以这样得到它：

jsonName["variableKeyName"];

( https://www.w3schools.com/js/js_json_syntax.asp )

所以你可以这样改变你的代码：

 var myObj = {name: "John", age: 31}; // dataset #1 var myObj2 = {month: "January", day: 20}; //dataset #2 function myFunction(jsonName, variableKeyName) { var variableKeyValue = jsonName[variableKeyName]; console.log(variableKeyValue ); } myFunction(myObj, "name"); //this prints "John" myFunction(myObj2, "day"); //this prints "20"