How can I use variables as the pattern and the replacement of replaceAll() method?

I have a form, and once the submit button is clicked, an object is generated. Each key-value pair is built following this pattern: inputId: inputValue, so the object looks like this:

let inputsObj = {
   templateList: 'blank',
   agentsName: 'John',
   agentsPhone: '000-000-0000'
}

I then need to replace all instances of the inputIds inside a string. So the string looks like this:

let template = "My name is agentsName and this is my phone number: agentsPhone"

and I need to make it look like this:

"My name is John and this is my phone number: 000-000-0000"

The number of input fields is unknown (since it depends on other things) and they won't always be the same. So I'm trying to create a function to replace these placeholders dynamically. I'm trying to loop through the inputsObj and then replace each key with its value:

let finalTemplate

const getReplacements = () => {
   for (let replacement in inputsObj) {
       finalTemplate = template.replaceAll(replacement, inputsObj[replacement])
            return finalTemplate
   }
   return finalTemplate
}

For example, replacement would be agentsName and inputsObj[replacement] should be John (and it would loop through the entire object in order to get all of the key-value pairs).

But this doesn't work. I'm guessing it's because I'm trying to use variables as the pattern and the replacement (it did work when I tried using regular strings instead, so I know everything else is working fine). But I don't know how to solve this. Any ideas?

EDIT:
I tried using template literals and it didn't work

You can make replacement like this in your example, you should only return the result at the end of your function:

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

let inputsObj = {
   templateList: 'blank',
   agentsName: 'John',
   agentsPhone: '000-000-0000'
}


let template = "My name is agentsName and this is my phone number: agentsPhone"

const getReplacements = () => {
   for (let replacement in inputsObj) {
        template = template.replaceAll(replacement, inputsObj[replacement])
   }
   return template
}

console.log(getReplacements());

<!-- end snippet -->

Alternatively you can get array of keys with Object.keys method and use reduce for shorter syntax:

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

let inputsObj = {
  templateList: 'blank',
  agentsName: 'John',
  agentsPhone: '000-000-0000'
};

let template = "My name is agentsName and this is my phone number: agentsPhone";


const getReplacements = () => Object.keys(inputsObj).reduce((acc, key) => acc.replaceAll(key, inputsObj[key]), template)

console.log(getReplacements())

<!-- end snippet -->

1. You can't return in first iteration of the loop
2. You have to use replaceAll on finalTemplate

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

let inputsObj = {
  templateList: 'blank',
  agentsName: 'John',
  agentsPhone: '000-000-0000'
}

let template = "My name is agentsName and this is my phone number: agentsPhone"

const getReplacements = () => {
  let finalTemplate = template

  for (let replacement in inputsObj) {
    finalTemplate = finalTemplate.replaceAll(replacement, inputsObj[replacement])
  }
  return finalTemplate
}

console.log(getReplacements())

<!-- end snippet -->

Simply use template littérals for that

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

let inputsObj = 
  { templateList : 'blank'
  , agentsName   : 'John'
  , agentsPhone  : '000-000-0000'
  };

const getReplacements = ({agentsName, agentsPhone}) => 
  `My name is ${agentsName} and this is my phone number: ${agentsPhone}`;


console.log(getReplacements(inputsObj))

<!-- end snippet -->