Basics

Gun.js has some core APIs. It's essential for you to understand those basics before getting started.

• gun.get
• gun.put

---

• gun.once
• gun.on

---

• gun.set
• gun.map
• gun.unset

Step 0, know how to install and start a gun instance

Installation

npm install gun

Start Server

cd node_modules/gun && npm start

Import it

import Gun from 'gun/gun'
require('gun/sea') // matters if you want to use User System
require('gun/lib/unset.js')

var gun = Gun(['http://localhost:8765/gun'])
let user = gun.user()

Step 1, know what is gun

gun is an object. It's kind of like a class in python.

What can you do with a class? call functions from it! Just add a dot before your function name, that should do it. For example: gun.get()

Step 2, know how to set a variable

Just call

gun.get("my_name").put("yingshaoxo")

It is equate to python version of

gun['my_name'] = 'yingshaoxo'

Step 3, know how to read a variable

Just call

gun.get("my_name").once((value) => {
    window.console.log(value)
    // it'll print out "yingshaoxo"
})

It is equate to python version of

value = gun['my_name']
print(value)
# it'll print out "yingshaoxo"

Step 4, know how to get a variable when it's getting changed

Just call

gun.get("my_name").put("yingshaoxo")
gun.get("my_name").on((value) => {
    window.console.log(value)
    // it'll print out "yingshaoxo"
})

gun.get("my_name").put("was great!")
// it'll print out "was great" even if you didn't call once() function again

Step 5, how to use set() function

set is a mathematical term. Every element or object in a set should be different than each other in that set. (If you knew python, you should know what I mean.)

Say if we want to save two objects into gun database, what we do is:

object_a = {
    'username': "yingshaoxo",
    'password': 'i_love_you'
}

object_b = {
    'username': "dear_reader",
    'password': 'i_love_you_too'
}

gun.get("users").set(object_a)
gun.get("users").set(object_b)

// Now you should have object_a and object_b under the property of "users"
// Gun set is very special, he can only save object, no list, no map, no variable, just object, remember that!

Step 6, how to read data from our set?

gun.get("users").map().once((object) => {
    let username = object.username
    let password = object.password
    window.console.log(username, password)
})

Step 7, how to remove an object from our set?

require('gun/lib/unset.js')

object_a = {
    'username': "yingshaoxo",
    'password': 'i_love_you'
}

gun.get("users").unset(object_a)
// Now only the object_b is left

User System

For the previous section, we've discussed the basics. If you smart enough, you'll notice by using the global gun object to save and read data is not secure. Everyone who is able to use gun.js can change the data. So we need to introduce a secure system for you: the User System.

• gun.user.create
• gun.user.auth
• gun.user.is
• gun.user.leave

First, we create a user

let username = "yingshaoxo"
let password = "i_love_you"

user.create(username, password, (feedback) => {
    if ("ok" in feedback) {
        window.console.log("You have created a new user!")
    } else if ("err" in feedback) {
        window.console.log(feedback.err)
    }
})

Then, we log into our account

let username = "yingshaoxo"
let password = "i_love_you"

user.auth(username, password, (feedback) => {
    if ("gun" in feedback) {
        window.console.log("You have logged into your account!")
    } else if ("err" in feedback) {
        window.console.log(feedback.err)
    }
})

How to know if a user is currently logged in?

if (user.is) {
    window.console.log("Welcome! You are my god.")
} else {
    window.console.log("Go away! You are nobody.")
}

Can we logout?

user.leave()

Save data under a specific user

let username = "yingshaoxo"
let password = "i_love_you"

let gun_of_this_user = null

user.auth(username, password, (feedback) => {
    if ("gun" in feedback) {
        gun_of_this_user = feedback.gun
    }
})

gun_of_this_user.get("my_data").put({
    love: "beautiful woman",
    love_to_do: "speak English and coding"
})

The author of gun.js, Mark Nadal think that everyone in this world should have a gun to protect their own freedom. I agree with that. And I think the whole US people will also stand on this.

This data will only be saved under the user yingshaoxo. You will not be able to get it from the global gun objct.

Find a specific user, and read his data

Find a user by name

let username = "yingshaoxo"

gun.get('~@' + username).once((data, _) => {
    let obj = data["my_data"]

    let a_thing = obj.love
    let an_action = obj.love_to_do

    window.console.log("this user love " + a_thing + " and love to " + an_action)
});

Find a user by public key

Sometimes username is not enough for identifying a unique person, so we use public_key instead.

let username = "yingshaoxo"
let password = "i_love_you"

let public_key = null

/*
user.create(username, password, (feedback) => {
    if ("ok" in feedback) {
        public_key = feedback.pub
    }
})
*/

user.auth(username, password, (feedback) => {
    if ("gun" in feedback) {
        public_key = feedback.get.slice(1,)
    }
})

gun.user(public_key).once((data) => {
    let obj = data["my_data"]

    let a_thing = obj.love
    let an_action = obj.love_to_do

    window.console.log("this user love " + a_thing + " and love to " + an_action)
})

Conclusion

That's all I could teach you.

Are you ready to die for the freedom of humanity?

Let's Go!