JSFiddle - React, Tailwind, and code Playground

by AndyE

HTML

<div id="test"></div>

JavaScript

var elem = document.getElementById('test');  // simple div element.
var result;               // store result returned.

function test_func(){};   // function declaration.
                          // function expression behaves identically.

elem.onclick = test_func; // assign test_func to element's onclick.

// DIRECT CALL
test_func();                 // works
test_func( true );           // works
result = test_func();        // works
result = test_func( true );  // works

// DIRECT CALL, CHANGING THE CONTEXT TO THE ELEMENT
test_func.call( elem );                  // works
test_func.call( elem, true );            // works
result = test_func.call( elem );         // works
result = test_func.call( elem, true );   // works ******** (surprising)

// CALL VIA ELEMENT, USING .call() METHOD, CHANGING THE CONTEXT TO THE ELEMENT
elem.onclick.call( elem );                  // works
elem.onclick.call( elem, true );            // works
result = elem.onclick.call( elem );         // works
result = elem.onclick.call( elem, true );   // works ******** ( very surprising)

// CALL VIA ELEMENT
elem.onclick();                 // works
elem.onclick( true );           // works
result = elem.onclick();        // works
result = elem.onclick( true );  // Error: Object doesn't support this action