This package implements the levelup interface, and at the same time wraps https://www.npmjs.com/package/levelup so you can use any of the supported leveldown backends.
package main
import (
"github.com/fiatjaf/go-levelup"
"github.com/fiatjaf/go-levelup-js"
"github.com/fiatjaf/levelup/stringlevelup"
)
func main() {
bdb := levelupjs.NewDatabase("my-beautiful-browser-database", "fruitdown")
defer bdb.Erase()
db := stringlevelup.StringDB(bdb)
fmt.Println("setting key1 to x")
db.Put("key1", "x")
res, _ := db.Get("key1")
fmt.Println("setting key2 to 2")
fmt.Println("res at key2: ", res)
db.Put("key2", "y")
res, _ = db.Get("key2")
fmt.Println("res at key2: ", res)
fmt.Println("deleting key1")
db.Del("key1")
res, _ = db.Get("key1")
fmt.Println("res at key1: ", res)
fmt.Println("batch")
db.Batch([]levelup.Operation{
stringlevelup.Put("key2", "w"),
stringlevelup.Put("key3", "z"),
stringlevelup.Del("key1"),
stringlevelup.Put("key1", "t"),
stringlevelup.Put("key4", "m"),
stringlevelup.Put("key5", "n"),
stringlevelup.Del("key3"),
})
res, _ = db.Get("key1")
fmt.Println("res at key1: ", res)
res, _ = db.Get("key2")
fmt.Println("res at key2: ", res)
res, _ = db.Get("key3")
fmt.Println("res at key3: ", res)
fmt.Println("reading all")
iter := db.ReadRange(nil)
for ; iter.Valid(); iter.Next() {
fmt.Println("row: ", iter.Key(), " ", iter.Value())
}
fmt.Println("iter error: ", iter.Error())
iter.Release()if you don't call stringlevelup.StringDB on the object returned by NewDatabase you still can use the same methods, only replacing all string arguments with []byte (returned values will also be bytes). I've just used the string approach here for readability, but it is slower.
levelupjs will try to require() both levelup and the name of the adapter you gave. If require is not available it will try to load these from the global namespace, so window.levelup and window[adapterName] must be set. If you're running this on a Node.js environment you should be fine with the above instructions, but if you're just using raw HTML you'll have to include these dependencies before, like:
You can just include levelup and the adapter of your choice. They will be picked from the global namespace.
<!doctype html>
<script src=https://wzrd.in/standalone/levelup></script>
<script src=https://wzrd.in/standalone/fruitdown></script>
<script src=your-script-that-includes-levelupjs-somehow.js></script>If you're using Webpack, this is probably what you have to do.
For the JS libraries to be available for being required from the GopherJS environment they must be "globally" requireable, that's not possible if you do the normal browserifying stuff, but it is if you bundle them the following way:
go get github.com/fiatjaf/go-levelup-js
npm install levelup
npm install fruitdown # or other adapter, you probably want 'memdown' for testing.
browserify your-script.js -r levelup -r memdown -o bundle.jsThen include bundle.js in the HTML.
go get github.com/fiatjaf/go-levelup-js
npm install levelup
npm install fruitdown # or other adapter, you probably want 'memdown' for testing.
gopherjs run your-script.go