93 lines
2.1 KiB
Go
93 lines
2.1 KiB
Go
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//go:build js
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package main
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import (
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"bytes"
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"encoding/json"
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"syscall/js"
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"text/template"
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)
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func main() {
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regenChan := make(chan struct{})
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go executeTemplate(regenChan)
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eventListener := func(this js.Value, args []js.Value) interface{} {
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ev := args[0]
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ev.Call("preventDefault")
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regenChan <- struct{}{}
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return nil
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}
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querySelector("#template").Call("addEventListener", "keyup", js.FuncOf(eventListener))
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querySelector("#data").Call("addEventListener", "keyup", js.FuncOf(eventListener))
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regenChan <- struct{}{}
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<-make(chan struct{})
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}
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func executeTemplate(regenChan chan struct{}) {
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templateEl := querySelector("#template")
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dataEl := querySelector("#data")
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outputEl := querySelector("#output")
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tmplMessageEl := querySelector("#template-message")
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dataMessageEl := querySelector("#data-message")
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displayErrors := func(dataErr error, tmplErr error) {
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if dataErr != nil {
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dataMessageEl.Set("innerText", dataErr.Error())
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} else {
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dataMessageEl.Set("innerText", "")
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}
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if tmplErr != nil {
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tmplMessageEl.Set("innerText", tmplErr.Error())
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} else {
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tmplMessageEl.Set("innerText", "")
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}
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}
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var templateSource string
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var tmpl *template.Template
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setTemplateSource := func(newTemplateSource string) (*template.Template, error) {
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if tmpl == nil || templateSource != newTemplateSource {
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newTmpl := template.New("")
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if _, err := newTmpl.Parse(newTemplateSource); err != nil {
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return nil, err
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}
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tmpl = newTmpl
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}
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return tmpl, nil
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}
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var outBuf bytes.Buffer
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for range regenChan {
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templateValue := templateEl.Get("value").String()
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dataValue := dataEl.Get("value").String()
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var dataJson interface{}
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dataErr := json.Unmarshal([]byte(dataValue), &dataJson)
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tmplInst, tmplErr := setTemplateSource(templateValue)
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if dataErr != nil || tmplErr != nil {
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displayErrors(dataErr, tmplErr)
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continue
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}
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outBuf.Reset()
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if err := tmplInst.Execute(&outBuf, dataJson); err != nil {
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displayErrors(nil, err)
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continue
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}
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outputEl.Set("innerText", outBuf.String())
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displayErrors(nil, nil)
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}
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}
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func querySelector(query string) js.Value {
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return js.Global().Get("document").Call("querySelector", query)
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}
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