new member messages discord

Discord Join Messages.js

loading lines: "https://gist.github.com/fourjr/f94fc112cef6da07fc274216d5755420"

Somewhere in 2020, they reduced the messages from 38 to 13.. This is the updated list on 5 December 2020.
Ctrl+Shift+I > Application > Frames > top > Scripts > a3762dfb973e0a7a21ba.js > ctrl+f "GUILD_MEMBER_JOIN" or https://canary.discordapp.com/assets/a3762dfb973e0a7a21ba.js

        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_001: "[!!{username}!!](usernameOnClick) joined the party.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_002: "[!!{username}!!](usernameOnClick) is here.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_003: "Welcome, [!!{username}!!](usernameOnClick). We hope you brought pizza.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_004: "A wild [!!{username}!!](usernameOnClick) appeared.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_005: "[!!{username}!!](usernameOnClick) just landed.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_006: "[!!{username}!!](usernameOnClick) just slid into the server.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_007: "[!!{username}!!](usernameOnClick) just showed up!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_008: "Welcome [!!{username}!!](usernameOnClick). Say hi!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_009: "[!!{username}!!](usernameOnClick) hopped into the server.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_010: "Everyone welcome [!!{username}!!](usernameOnClick)!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_011: "Glad you're here, [!!{username}!!](usernameOnClick).",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_012: "Good to see you, [!!{username}!!](usernameOnClick).",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_013: "Yay you made it, [!!{username}!!](usernameOnClick)!",

**Early 2020
Ctrl+Shift+I > Application > Frames > top > Scripts > d584711e150c6741c5cc.js > ctrl+f "seems op" or https://canary.discordapp.com/assets/d584711e150c6741c5cc.js

        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN: "[!!{username}!!](usernameOnClick) just joined the server - glhf!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_01: "[!!{username}!!](usernameOnClick) just joined. Everyone, look busy!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_02: "[!!{username}!!](usernameOnClick) just joined. Can I get a heal?",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_03: "[!!{username}!!](usernameOnClick) joined your party.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_04: "[!!{username}!!](usernameOnClick) joined. You must construct additional pylons.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_05: "Ermagherd. [!!{username}!!](usernameOnClick) is here.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_06: "Welcome, [!!{username}!!](usernameOnClick). Stay awhile and listen.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_07: "Welcome, [!!{username}!!](usernameOnClick). We were expecting you ( ͡° ͜ʖ ͡°)",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_08: "Welcome, [!!{username}!!](usernameOnClick). We hope you brought pizza.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_09: "Welcome [!!{username}!!](usernameOnClick). Leave your weapons by the door.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_10: "A wild [!!{username}!!](usernameOnClick) appeared.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_11: "Swoooosh. [!!{username}!!](usernameOnClick) just landed.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_12: "Brace yourselves. [!!{username}!!](usernameOnClick) just joined the server.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_13: "[!!{username}!!](usernameOnClick) just joined. Hide your bananas.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_14: "[!!{username}!!](usernameOnClick) just arrived. Seems OP - please nerf.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_15: "[!!{username}!!](usernameOnClick) just slid into the server.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_16: "A [!!{username}!!](usernameOnClick) has spawned in the server.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_17: "Big [!!{username}!!](usernameOnClick) showed up!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_18: "Where’s [!!{username}!!](usernameOnClick)? In the server!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_19: "[!!{username}!!](usernameOnClick) hopped into the server. Kangaroo!!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_20: "[!!{username}!!](usernameOnClick) just showed up. Hold my beer.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_21: "Challenger approaching - [!!{username}!!](usernameOnClick) has appeared!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_22: "It's a bird! It's a plane! Nevermind, it's just [!!{username}!!](usernameOnClick).",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_23: "It's [!!{username}!!](usernameOnClick)! Praise the sun! \\\\[T]/",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_24: "Never gonna give [!!{username}!!](usernameOnClick) up. Never gonna let [!!{username}!!](usernameOnClick) down.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_25: "Ha! [!!{username}!!](usernameOnClick) has joined! You activated my trap card!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_26: "Cheers, love! [!!{username}!!](usernameOnClick)'s here!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_27: "Hey! Listen! [!!{username}!!](usernameOnClick) has joined!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_28: "We've been expecting you [!!{username}!!](usernameOnClick)",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_29: "It's dangerous to go alone, take [!!{username}!!](usernameOnClick)!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_30: "[!!{username}!!](usernameOnClick) has joined the server! It's super effective!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_31: "Cheers, love! [!!{username}!!](usernameOnClick) is here!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_32: "[!!{username}!!](usernameOnClick) is here, as the prophecy foretold.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_33: "[!!{username}!!](usernameOnClick) has arrived. Party's over.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_34: "Ready player [!!{username}!!](usernameOnClick)",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_35: "[!!{username}!!](usernameOnClick) is here to kick butt and chew bubblegum. And [!!{username}!!](usernameOnClick) is all out of gum.",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_36: "Hello. Is it [!!{username}!!](usernameOnClick) you're looking for?",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_37: "[!!{username}!!](usernameOnClick) has joined. Stay a while and listen!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_38: "Roses are red, violets are blue, [!!{username}!!](usernameOnClick) joined this server with you",

does anyone know how discord picks which message to use?

I think they pick random message

it is absolutely not random... If you open the discord app on mobile and on pc you will see the discord join messages are the same...
i got an answer to my question on reddit, some person read the source code... basically you create a discord snowflake from the timestamp and then do snowflake % array.length doing new Date(timestamp_string) % array.length seems to also work.

edit: made a simple mistake....

        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_26: "Cheers, love! [!!{username}!!](usernameOnClick)'s here!",
        SYSTEM_MESSAGE_GUILD_MEMBER_JOIN_31: "Cheers, love! [!!{username}!!](usernameOnClick) is here!",

Aren't these the same?

just got the roses are red violets are blue [name] just joined the guild with you