find members who have a role 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);