How would you turn a JavaScript variable into a Template literal?

Question

I would like to take text that I generated and stored in a string and use it like a template literal.

var generatedText = "Pretend this text was generated and then stored in a variable. "; 
generatedText = "But I still need to use it as a template it to get ${variable}.";

var variable = "Successs!!!!";

console.log(generatedText);
//prints 'But I still need to interpolate it to get ${variable}.'
//how can I make it print using variable in it like a template as if it were doing this
console.log(`But I still need to use it as a template it to get ${variable}.`);
//prints 'But I still need to use it as a template it to get Successs!!!!.'

How can I get generated text to become a template string?

generatedText must start in a variable so I need to find a way to convert it to a template string if possible.

Edit:

I didn't think I would have to put this but also I don't want to use eval to risk evaluating random code...

Answer 1

For the general situation, you can use a replacer function to replace every occurrence of ${someProp} with the someProp property on an object:

const interpolate = (str, obj) => str.replace(
  /\${([^}]+)}/g,
  (_, prop) => obj[prop]
);

const generatedText = "But I still need to use it as a template it to get ${variable}.";
const variable = "Successs!!!!";

console.log(interpolate(generatedText, { variable }));

The regular expression \${([^}]+)} means:

• \$ - Literal $
• { - Literal {
• ([^}]+) First (and only) capture group:
  • [^}]+ - One or more characters which are not }
• } - Literal }

Since prop is the property name found in between the brackets, replace with obj[prop] to replace with the desired replacement.