how do i resolve promises

Question

I read like through 10 pages on how to resolve promises but i still don't get it. Info: I want to fetch a specific member of a discord server

Currently I have a async function with the promise inside that returns it but it gives me a message with "Invalid Body Form"

async function mbr() {
     const mB = await client.guilds.cache.get("1037783624449282189").members.fetch(`${args[0]}`).then((m) => { return m; });
     return mB
}
let member = mbr()

if (member.roles.cache.has("1039983830389510305"))

Edit: It gives me this Error when i do a async Function inside a async function

G:\Desktop\Minecraft Modding\Bedrock\_____\Server\legend\plugins\nodejs\discord-bot\node_modules\@discordjs\rest\dist\index.js:659
        throw new DiscordAPIError(data, "code" in data ? data.code : data.error, status, method, url, requestData);
              ^

DiscordAPIError[50035]: Invalid Form Body
user_id[NUMBER_TYPE_COERCE]: Value "undefined" is not snowflake.
    at SequentialHandler.runRequest (G:\Desktop\Minecraft Modding\Bedrock\_____\Server\legend\plugins\nodejs\discord-bot\node_modules\@discordjs\rest\dist\index.js:659:15)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async SequentialHandler.queueRequest (G:\Desktop\Minecraft Modding\Bedrock\_____\Server\legend\plugins\nodejs\discord-bot\node_modules\@discordjs\rest\dist\index.js:458:14)
    at async REST.request (G:\Desktop\Minecraft Modding\Bedrock\_____\Server\legend\plugins\nodejs\discord-bot\node_modules\@discordjs\rest\dist\index.js:902:22)
    at async GuildMemberManager._fetchSingle (G:\Desktop\Minecraft Modding\Bedrock\_____\Server\legend\plugins\nodejs\discord-bot\node_modules\discord.js\src\managers\GuildMemberManager.js:489:18)
    at async mbr (G:\Desktop\Minecraft Modding\Bedrock\_____\Server\legend\plugins\nodejs\discord-bot\chatBridge\accountLink.js:8:32)
    at async G:\Desktop\Minecraft Modding\Bedrock\_____\Server\legend\plugins\nodejs\discord-bot\chatBridge\accountLink.js:11:30 {
  requestBody: { files: undefined, json: undefined },
  rawError: {
    code: 50035,
    errors: {
      user_id: {
        _errors: [
          {
            code: 'NUMBER_TYPE_COERCE',
            message: 'Value "undefined" is not snowflake.'
          }
        ]
      }
    },
    message: 'Invalid Form Body'
  },
  code: 50035,
  status: 400,
  method: 'GET',
  url: 'https://discord.com/api/v10/guilds/1037783624449282189/members/undefined'
}

Answer 1

Promises need to be awaited, either by using p.then(callback), or by using await p.

For example, this Promise:

const p = new Promise(resolve => setTimeout(resolve("Hello world!"), 100));

will resolve in 100 ms, and can be used either like this

p.then(message => console.log(message));

or like this

console.log(await p);

In short, your function:

async function mbr() {
     const mB = await client.guilds.cache.get("1037783624449282189").members.fetch(`${args[0]}`).then((m) => { return m; });
     return mB
}

can be resolved by either

mbr().then(member => {
   if (member.roles.cache.has("1039983830389510305")) { ... }
});

or

const member = await mbr();
if (member.roles.cache.has("1039983830389510305")) { ... }

Note that in order to use await, you must be in an async context! By default, Node.js's global scope is synchronous, so you need to wrap your code inside an anonymous async function, like so:

(async () => {

  const member = await mbr();
  if (member.roles.cache.has("1039983830389510305")) { ... }

})();  // <--  call immediately