how to get all of the roles from a member in discord.js code example

Example 1: get discord.js role

let role = message.guild.roles.cache.find(r => r.id === "Role ID");

// The member you want to add the role to
let member = message.mentions.members.first();

// Add role to the member
member.roles.add(role);

// Or add it to yourself
message.author.roles.add(role);

Example 2: discord.js get all members with role

//outputs the IDs of all members with the specified role as an array

// === discord.js v11 ===
message.guild.roles.get('ROLE-ID').members.map(m=>m.user.id);

// === discord.js v12 ===
message.guild.roles.cache.get('ROLE-ID').members.map(m=>m.user.id);