Run results for: let and return vs IIFE

Run details:

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Mobile Safari/537.36

Browser: Chrome Mobile 120

Operating system: Android

Device Platform: Mobile

Date tested: 2 years ago

Benchmark engine: Benchmark.js

IIFE

76K/s

let and return

73K/s

View exact numbers

Test name	Executions per second
✓ IIFE	76,214 Ops/sec
let and return	73,432 Ops/sec

HTML Preparation code:

<a id='test' href='#' />

Script Preparation code:

el=document.querySelector("#test");
isInViewportLet=e=>{
  let r;
  return (r=e.getBoundingClientRect(),
          0 <= r.y &&
          0 <= r.x &&
          r.bottom <= innerHeight &&
          r.right <= innerWidth &&
          r.y < r.bottom &&
          r.x < r.right
         )
};
isInViewportIIFE=e=>(
  (r=>(
    0 <= r.y &&
    0 <= r.x &&
    r.bottom <= innerHeight &&
    r.right <= innerWidth &&
    r.y < r.bottom &&
    r.x < r.right
  ))(e.getBoundingClientRect())
);

Tests:

let and return
isInViewportLet(el);
IIFE
isInViewportIIFE(el);

Run results for: let and return vs IIFE

Designed to measure the performance of a workaround where an IIFE is used to eliminate let and return statements, which makes the function shorter.

let and return

IIFE