Replace string value with javascript object

Question

I am currently making a small module for NodeJs. For which I need a small help.

I will tell it like this. I have a variable with string. It contains a string html va

Answer 1

This solution uses template strings to do everything you want.

This solution has the advantage that, in contrast to the naive roll-your-own regexp-based template replacement strategy as proposed in another answer, it supports arbitrary calculations, as in

replacer("My name is ${name.toUpperCase()}", {name: "Bob"});

In this version of replacer, we use new Function to create a function which takes the object properties as parameters, and returns the template passed in evaluated as a template string. Then we invoke that function with the values of the object properties.

function replacer(template, obj) {
  var keys = Object.keys(obj);
  var func = Function(...keys, "return `" + template + "`;");

  return func(...keys.map(k => obj[k]));
}

We define the template using ${} for substitutions (instead of $()), but escaping as \${ to prevent evaluation. (We could also just specify it as a regular string literal, but would then lose multi-line capability).

var html = `


  
    



  
Test file, \${text}
       


`;

Now things work exactly as you want:

replacer(html, { "title" : "my title", "text" : "text is this" });

Simple example:

> replacer("My name is ${name}", {name: "Bob"})
< "My name is Bob"

Here's an example of calculated fields:

> replacer("My name is ${name.toUpperCase()}", {name: "Bob"})
< "My name is BOB"

or even

> replacer("My name is ${last ? lastName : firstName}", 
    {lastName: "Jones", firstName: "Bob", last: true})
< "My name is Jones"