1 DOM 常用属性

let val;

val = document;
val = document.all;
val = document.all[2];
val = document.all.length;
val = document.head;
val = document.body;
val = document.doctype;
val = document.domain;
val = document.URL;
val = document.characterSet;
val = document.contentType;


val = document.forms;
val = document.forms[0];
val = document.forms[0].id;
val = document.forms[0].method;
val = document.forms[0].action;


val = document.links;
val = document.links[0];
val = document.links[0].id;
val = document.links[0].className;  // className
val = document.links[0].classList[0];	// classList

val = document.images;

val = document.scripts;
val = document.scripts[2].getAttribute('src');	// getAttribute

2 HTMLCollection转化为Array

let scripts = document.scripts;

let scriptsArr = Array.from(scripts);

scriptsArr.forEach(function(script) {
  console.log(script.getAttribute('src'));
});