Pass Golang Variables into Javascript

Question

I am trying to pass my Golang variables into a Javascript file. I have read multiple articles online, including How to pass variables and data from PHP to JavaScript?. I feel like I'm pretty close, but alas the most eloquent implementation to this problem eludes me.

I'm looking for a simple and elegant solution that injects an object value in Go with a variable in Javascript. I feel like this is a very common problem, so the lack of a clear tutorial on this surprises me.

My first file [server.go] servers an HTML page using the templating libraries in Golang passing in a context and serving them through Handlers.

type PassStruct struct{
    data    []int
    number1 int
    number2 int
}

//inject the structure into render
func render(w http.ResponseWriter, tmpl string, context Context){
       //parse context and fill in templating variables using template 
 }

I now have an HTML document that is served, which adds a Javascript file to it.

 <html>
     <head>
     //import javascript file 
     </head>
     <body>
     //some body
     </body>
 </html>

Finally, the javascript file is what I am really interested in:

  var data; //some 
  var number1;
  var number2;

  function doSomething(){
  }

I need to send the PassStruct into the Javascript file, and map out each of the values within the structure to a variable in the Javascript file. I have tried AJAX calls, but have not had success so far.

For most templating languages JSON encoding is the safest way, see https://gobyexample.com/json — Ruan Mendes, May 25 '16 at 11:57

Shubham Arora · Answer 1 · 2021-04-15T16:39:41.703

Finally , after spending 2 days on the problem , i found an elegant way to work around it . We will use templates to solve this problem .

Read about templates usage in golang here - Understanding Templates with Examples .

Here is a sample code to pass a golang variable called golangVar in javascript .

HTML_File -

<html>
<head>
    <script>
        var golangVar = "{{.}}"
        console.log(golangVar);
    </script>
 </head>
 <body>
 <!--some body-->
 </body>
</html>

Golang HttpHandler -

Make sure you include "html/template" library in the golang code .

func golangHttpHandler(w http.ResponseWriter, r *http.Request) {
var golangVar string 
golangVar = "ProblemSolved" 
templ, err := template.ParseFiles("/home/PathToHTMLPage/HTML_File.html")
if(err!=nil){
    fmt.Println("Error = ",err)
}
err = templ.Execute(w, golangVar)
if(err!=nil){
    fmt.Println("Error = ",err)
}   
}

Also, a bonus tip - If you are working around with buffalo framework for golang , you can use default plush package for templating . Its similar to what we have done here with just a little bit of change in syntax and passing of html file . Read - Templating in Buffalo Framework

HelloNewWorld · Answer 2 · 2016-12-23T05:50:13.357

This way maybe helpful:

Html:

<html>
    <head>
     <!--import javascript file -->
        <script type="text/javascript" src="static/myjs.js"></script>
        <script type="text/javascript">
            myFunc({{.}});
        </script>
     </head>
     <body>
     <!--some body-->
     </body>
</html>

Javascript:(myjs.js)

function myFunc(passStruct){
    var obj = Object();

    var data = passStruct.Data;
    var number1=passStruct.Number1;
    var number2=passStruct.Number2;

    obj.data=data;
    obj.number1=number1;
    obj.number2=number2;

    return obj;
 }

score 0 · Answer 3 · answered May 05 '22 at 11:29

0

You can write your own template function and use it to marshal struct into json.

See my answer here.

answered May 05 '22 at 11:29

joeyave

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Pass Golang Variables into Javascript

3 Answers3