*/

const value = func ();
const c = typeof undefined;
console.log( c );

const el = document.querySelector("div.user-panel.main input[name='login']");
const matches = container.querySelectorAll("li[data-active='1']");

const arrayEmpty = new Array();
Array.isArray([1, 3, 5])
const fruits = [];
const firstElement = array1.shift();

const o = new Object();
o.foo = 42;
const person = {};

if (a > 0) {
    
} else {
    
}

1 === ""
 && NaN
 || null

const func2 = (x, y) => {
    return false;
}

async

const words = str.split(" ");

arraySparse.forEach((element) => {
  const count = animals.push("cows");
});

clothing.length;

const result = words.filter((word) => word.length > 6);

for (let i = 0; i < 9; i++) {
  str = str + i;
}

node.parentNode;

dog1.toString();

str1.padStart(2, "0");

const regExp = /ab+c/i;
let result = /^hello/.test(str);
const found = paragraph.match(regex);

const newDiv = document.createElement("div");
newDiv.textContent = "This text is different!";
document.body.appendChild(p);

const fragment = new DocumentFragment();
parentDiv.insertBefore(newNode, parentDiv.firstChild);

my_element.addEventListener("click", () => {
    
});

change

mouseover

mouseleave

mouseout

switch (foo) {
  case -1:
    console.log("负 1");
    break;
  case 2:
    console.log(2);
    break;
  default:
    console.log("default");
}

let l = '';
var v = `${c} 小于 ${l}`;

/*

*/
console.log('it works!');
/*

/**/
console.log('it works!');
/*

*/
console.log('it works!');
/*/*