摘要：
var oScript = document.createElement('script'); oScript.type = 'text/javascript'; oScript.src = "xx.js"; /* ** script标签的onload和onreadystatechange事件 ** 阅读全文
摘要：
let a = undefined; let b = null; let c = ''; let d = 0; let e = {}; let f = []; if (a) { console.log("undefined 能过"); } else { console.log("undefined 阅读全文