how do I replace a variable in a template string in Javascript?

Question

Here's what I'm trying to achieve.

let something = 'first string';
let template = `asdf=${something}asdf`;

some.method(template)
    .then(function() {
       let something = 'new string';
       console.log(template); 
       // does not return 'asdf=new stringasdf' like expected
    });

How would I keep the template, but switch out a variable inside it whenever I want (inside a scoped function)?

Answer 1

The template is basically shorthand for:

let template = "asdf=" + something + "asdf";

So it is evaluated at the place the template itself appears in the code.

I think you'll want to use a function:

let template = function(something) { return `asdf=${something}asdf`; }

Then you can do:

some.method(template(something)).then(function() { let something = 'new string'; console.log(template(something)); });

Answer 2

Check this function I wrote out:

GitHub: https://github.com/tjcafferkey/stringinject/blob/master/src/index.js

NPM: https://www.npmjs.com/package/stringinject

Allows you to do the following:

var str = "This is a {0} string for {1}"
var newStr = stringInject(str, ["test", "stringInject"]);

// This is a test string for stringInject