Better solution for forEach and if ? map, filter Javascript

Question

I really need bettter solution for this logic:

    this.allClients.forEach(obj => {
     if(obj.status === 2) {
       this.numOfWaitingUsers.push(obj) 
     }
     if(obj.status === 1) {
      this.numOfInactiveUsers.push(obj) 
    }
    if(obj.status === 0) {
      this.numOfActiveUsers.push(obj) 
    }
    if(obj.status === 3) {
      this.numOfAClosedUsers.push(obj) 
    }
    })

This is work perfect but i need better soluiton. i know to can be better with less code.

Answer 1

One solution would be to map from the status number to the array property name, like this:

const arrayNameByStatus = {    // This could be an array, but I wasn't sure if
    0: "numOfActiveUsers",     // status codes were necessarily contiguous like
    1: "numOfInactiveUsers",   // they are in the question
    2: "numOfWaitingUsers",
    3: "numOfAClosedUsers",
};
for (const obj of this.allClients) {
    const name = arrayNameByStatus[obj.status];
    if (name) { // Remove this for an error if status is an unexpected value
        this[name].push(obj);
    }
}

Live Example:

 const arrayNameByStatus = { 0: "numOfActiveUsers", 1: "numOfInactiveUsers", 2: "numOfWaitingUsers", 3: "numOfAClosedUsers", }; class Example { constructor() { this.allClients = [ {status: 0}, {status: 2}, {status: 2}, ]; this.numOfActiveUsers = []; this.numOfInactiveUsers = []; this.numOfWaitingUsers = []; this.numOfAClosedUsers = []; } method() { for (const obj of this.allClients) { const name = arrayNameByStatus[obj.status]; if (name) { this[name].push(obj); } } } } const e = new Example(); e.method(); console.log(e);

But , if you're going to index by status regularly, you might consider changing the structure of your object to support that directly. For instance, you might have a userCounts property that's an object with keys 0 through 3, which would let you index in directly:

// **IF** you change the structure so that `this` has a `userCounts`
// keyed by status:
for (const obj of this.allClients) {
    const array = this.userCounts[obj.status];
    if (array) { // Remove this for an error if status is an unexpected value
        array.push(obj);
    }
}

Live Example:

 class Example { constructor() { this.allClients = [ {status: 0}, {status: 2}, {status: 2}, ]; this.userCounts = { 0: [], 1: [], 2: [], 3: [], }; } method() { for (const obj of this.allClients) { const array = this.userCounts[obj.status]; if (array) { array.push(obj); } } } } const e = new Example(); e.method(); console.log(e);

Answer 2

Honestly, the code you've posted looks perfectly fine. However, if you had lots more if statements to go through, you could optimize it like the following:

// use the corresponding status as the key to access each array
let dataContainer = {
  0: this.numOfActiveUsers,
  1: this.numOfInactiveUsers,
  2: this.numOfWaitingUsers,
  3: this.numOfAClosedUsers
}
this.allClients.forEach(obj => dataContainer[obj.status].push(obj))

Answer 3

Use a lookup table for your status codes:

// const countNames = {0:"numOfActiveUsers", 1:"numOfInactiveUsers", 2:"numOfWaitingUsers", 3:"numOfAClosedUsers"};
const countNames = ["numOfActiveUsers", "numOfInactiveUsers", "numOfWaitingUsers", "numOfAClosedUsers"];
for (const obj of this.allClients) {
    const count = countNames[obj.status];
    if (count)
        this[count].push(obj) 
}