a look back at the evolution of string "merging" in javascript

merge-strings-sample.js

/** EXAMPLE */
//? start

//* legacy

var prefix = 'x'
var infix = 'y'
/** suffix argument */
var affix = 'id="';
affix += prefix + '-';
affix += infix + '-';
if (suffix !== null && typeof suffix !== 'undefined')
  affix += newSuffix();
else
  affix += 'z';
affix += '"';

//* outdated

var prefix = 'x'
var infix = 'y'
/** suffix param */
suffix = !Boolean(suffix) ? newSuffix() : 'z';
let affix = prefix + '-' + infix + '-' + suffix;
affix = 'id="' + affix + '"';

//* depreciated

const prefix = 'x'
const infix = 'y'
/** suffix arg */
const affix = `id="${[
  prefix,
  infix,
  suffix || newSuffix() || 'z'
].join('-')}"`;

//* modern

const prefix = 'x'
const infix = 'y'
/** suffix prop (defaults to "z") */
const affix = `id="${prefix}-${infix}-${
  suffix ??= newSuffix()
}"`;

// -> String(id="x-y-z")

//! end