javascript - How to take out the key value whose key value is true in object, and then join(',')

Question

How to take out the key value in the object whose key value is true, and then join(','). The current data structure is, ,
send_message:{1: true,2:true}, the data structure I want to give to the background is: send_message=1,2&is_live=1

Answer 1

Use for...in...:
This way:

const message = { 1: true, 2: true, 3: false };
const arr = [];
for (let item in message) {
    if (message[item]) {
        arr.push(item);
    }
}
console.log(arr.join(','));

Answer 2

Object.keys(message).filter(k => message[k] === true).join(',')