Using conditionals inside template literals

If you have a simple condition to check, use the ternary operator, as it as been said, but if you have more complex or nested conditions, just call a function in this way:

const canDrink = (age, hasToDrive) => {
  if (age >= 18 && !hasToDrive ) {
    return 'Yeah, no problem'
  } else if ( age >= 18 && hasToDrive ){
    return 'Maybe not that much'
  } else {
    return 'Not at all'
  }
}

console.log(`Can you drink tonight? ${ canDrink(21, true) }`) // Can you drink tonight? Maybe not that much

Use this:

let a = `test${conditional ? a : b} more text`;

You can also expand this a bit further and use placeholders inside such a conditional.

It really depends on the use case you have which is the most readable.

Some examples:

// example 1
const title = 'title 1';
const html1 = `${title ? `<h2>${title}</h2>` : '<h2>nothing 1</h2>'}`

document.getElementById('title-container-1').innerHTML = html1;

// example 2
const title2= 'title 2';
const html2 = `
	${title2 ? 
  	`<h2>${title2}</h2>` : 
  	"<h2>nothing 2</h2>"
  }`

document.getElementById('title-container-2').innerHTML = html2;

// example 3
const object = {
	title: 'title 3'
};

const html3 = `
	${(title => {
      if (title) {
        return `<h2>${title}</h2>`;
      }
	  	return '<h2>Nothing 3</h2>';
		})(object.title)
	  }
`;

document.getElementById('title-container-3').innerHTML = html3;
<div id="title-container-1"></div>
<div id="title-container-2"></div>
<div id="title-container-3"></div>

(source)