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Rediscovering JavaScript: ES6, ES7 & ES8

Solution Review: Tagged Template

Explore how to create a tagged template function that transforms embedded expressions to uppercase and eliminates leading whitespace using regex. Understand the use of spread operators, map, join, and trim methods to manipulate template literals effectively in JavaScript.

We'll cover the following...

Solution

We will review the following solution step-by-step.

Javascript (babel-node)
'use strict';
const stripMargin = function(texts, ...expressions) {
  const exceptLast = expressions.map(function(expression, index) {
    return `${texts[index]}${expression.toString().toUpperCase()}`;
  }).join('');
  const result = `${exceptLast}${texts[texts.length - 1]}`;
  return result.replace(/[\n][\t\s]+(\w)/g, ' $1').trim();
};
const name = 'Jane';
const processed = stripMargin` This is for 
  ${name} and it needs to be
    delivered by December 24th.`
    
console.log(processed);
//This is for JANE and it needs to be delivered by December 24th.

Explanation

There are two main functionalities that tag stripMargin has to implement to get the desired output.

  1. Convert all expressions to upper case
  2. Remove all leading spaces and indentations on the new lines

So, let’s start with the first one.

Converting expressions

In the function definition at line 3, we are taking two parameters:

  1. texts
  2. expressions

expressions

The ...