Run results for: Using a global context variable versus getting the context on each draw call

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.116 Safari/537.36 Edg/83.0.478.61

Browser: Chrome 83

Operating system: Windows

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
Using a global context variable	1796.8 Ops/sec
Invoking getContext() before every fillRect()	1017.4 Ops/sec

HTML Preparation code:

<canvas id="canvas" width="800" height="300"></canvas>

Script Preparation code:

$canvas = document.getElementById('canvas');
$context = $canvas.getContext('2d');
$context.clearRect(0, 0, 800, 300);

$iterations = 500;

Tests:

Using a global context variable
for (let i=0; i<$iterations; ++i) { $context.fillStyle = 'rgba(100,150,200,0.9)'; $context.fillRect(0, 0, 1, 1); }
Invoking getContext() before every fillRect()
for (let i=0; i<$iterations; ++i) { const context = $canvas.getContext('2d'); context.fillStyle = 'rgba(100,150,200,0.9)'; context.fillRect(0, 0, 1, 1); }