For anyone else with the same issue the html in the return statement is surrounded by backticks and not single quotes or double quotes. That was my mistake

from javascript-basic-projects.

const menu = [
{ title: 'Item 1' },
{ title: 'Item 2' },
{ title: 'Item 3' }
];

const sectionCenter = document.querySelector('.section-center');

window.addEventListener('DOMContentLoaded', function() {
let displayMenu = menu.map(function(item) {
return <h1>${item.title}</h1>;
});
console.log(displayMenu);
});

this is the right version......The template string should use backticks (``) instead of regular quotes for string interpolation. So, it should be <h1>${item.title}</h1> instead of "

${item.title}

from javascript-basic-projects.

Just replace inverted commas with backtics (""=> ``)
<h1>${item.title}</h1>

from javascript-basic-projects.