ES6 String interpolation from file content

Question

I came across the String interpolation feature in ES6. It works if I define the raw string in the code. But I want to read the raw string from a file and then replace the placeholders. How to do it?

file.txt

   hello ${customer.name} 

Node JS

   var customer = {name: 'sid'};
   var data = fs.readFileSync("file.txt","utf8");
   // what should go here so that data is 'Hello sid'?

Answer 1

You can build a one-liner instead of loading a template engine. This will replace ${field} with values from an object.

var obj = {a: 'one', b: 'two'};
var templ = '${a}, ${b}';

templ.replace(/\${([^}]*)}/g, (r,k)=>obj[k]);

//  'one, two'

Answer 2

I decided to go with es6-template-strings as it seems straight forward. Alternatively, handlebar is also good for complex expressions.Petr's suggestion to use eval also works but I have some constraints using eval for my project

var data = fs.readFileSync("file.txt","utf8");
var compiled = compile(data);
var content = resolveToString(compiled, customer);