在Javascript中将对象属性转换为逗号分隔值

Question

Here I want to convert object properties to comma separated values like following- Join the elements of an array into a string:

var fruits = {"f1":"Banana", "f2":"Orange", "f3":"Apple","f4":"Mango"};
var energy = Object.keys(fruits).map(function(k){return fruits[k]}).join(",");

The result of energy will be:

Banana,Orange,Apple,Mango

But When I apply like this-

 var fruits = {"f1":"Banana", "f2":"null", "f3":"Apple","f4":"Mango"};
 var energy = Object.keys(fruits).map(function(k){return fruits[k]}).join(",");

The result of energy is like this:

Banana,,Apple,Mango

And I want result like this-

Banana,null,Apple,Mango

I have tried these links but No luck found.

Easy way to turn properties of Javascript object into comma-separated list?

Updated the Question

var fruits = {"f1":"Banana", "f2":"", "f3":"Apple","f4":"Mango"};
var energy = Object.keys(fruits).map(function(k){return fruits[k]}).join(",");

The result of energy is like this:

Banana,,Apple,Mango

I want result like this-

 Banana,null,Apple,Mango

Answer 1

Using Object.values would be easier.

 // for "null" var fruits = {"f1":"Banana", "f2":"null", "f3":"Apple","f4":"Mango"}; var energy = Object.values(fruits).join(","); console.log(energy); // for null var fruits = {"f1":"Banana", "f2":null, "f3":"Apple","f4":"Mango"}; var energy = Object.values(fruits).map(String).join(","); console.log(energy); // for "" var fruits = {"f1":"Banana", "f2":"", "f3":"Apple","f4":"Mango"}; var energy = Object.values(fruits).map(v=>v===""?"null":String(v)).join(","); console.log(energy);

Answer 2

var fruits = {"f1":"Banana", "f2":"", "f3":"Apple","f4":"Mango"};
var energy = Object.keys(fruits).map(function(k){
    if(fruits [k] ==="") return "null";
    return fruits [k]        
    }).join(",");

Answer 3

about join() ,not show value null as string "null" , you can check it in map() same as below :

 const fruits = {"f1":"Banana", "f2":"", "f3":"Apple","f4":"Mango"}; const energy = Object.values(fruits).map(function(value){ return !value ? "null" : value; }).join(","); console.log(energy);