<style>
.classA {
 color: blue;
}
.classB {
 color: red;
}
</style>
<p class="classB classA">123</p>

let a = 0;
console.log(a);
console.log(b);
let b = 0;
console.log(c);
function c() {}

function a(b, c) {
  function b(){};
  alert(b);
}
a(1, 2);

function a(b, c) {
  var b;
  alert(b);
}
a(1, 2);

function Parent() {}
var p = new Parent()

console.log(1);
setTimeout(() => {
console.log(2);
});
new Promise(resolve => {
console.log(5);
resolve();
console.log(6);
}).then(() => {
console.log(7);
});
Promise.resolve().then(() => {
console.log(8);
process.nextTick(() => {
  console.log(9);
});
});