Python自动化开发学习18-Web前端
js正则表达式
test --判断字符串是否符合规定的正则，返回布尔值（true 或 false）
exec --获取匹配的数据，匹配不到则返回 null。返回一个数组，可以对返回的结果再次匹配。
首先要创建正则表达式对象
python中的写法是a = “字符串”
js中的写法是用/ /：rel = /\d+/
rel = /\d+/ //匹配数字 /\d+/ rel.test("dfsdfsfs454fgfgdfgfgf") true rel.test("dfsdfsfsfgfgdfgfgf") false rel.exec("dfsdfsfs454fgfgdfgfgf") ["454", index: 8, input: "dfsdfsfs454fgfgdfgfgf", groups: undefined]
匹配纯数字
rel = /^\d+$/; /^\d+$/ rel.test("12345") true rel.test("123df45") false
/\b \b /：表示匹配的是单词，中间有空格的字符串
(\w)加括号表示分组匹配，会先整体匹配，再在每个分组中匹配，这次只匹配分组的内容
/……/g:全局匹配
/……/i:不区分大小写
/……/m:匹配多行，默认是多行匹配，但是想匹配有^,$的，就需要在后面加上m了
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reg = /\bjava\w*\b/; /\bjava\w*\b/ text = "JavaScript is more fun than Java or JavaBeans!"; "JavaScript is more fun than Java or JavaBeans!" reg.exec(text) null reg = /\bJava\w*\b/; /\bJava\w*\b/ reg.exec(text) ["JavaScript", index: 0, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg = /Java(\w*)/; /Java(\w*)/ reg.exec(text) (2) ["JavaScript", "Script", index: 0, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg = /\bJava(\w*)\b/; /\bJava(\w*)\b/ reg.exec(text) (2) ["JavaScript", "Script", index: 0, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg = /Java(\w*)/g; /Java(\w*)/g reg.exec(text) (2) ["JavaScript", "Script", index: 0, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg = /Java\w*/g; /Java\w*/g reg.exec(text) ["JavaScript", index: 0, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] text = "JavaScript is more fun than Java or JavaBeans!"; "JavaScript is more fun than Java or JavaBeans!" reg = /Java\w*/g; /Java\w*/g reg.exec(text) ["JavaScript", index: 0, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg = /\bJava(\w*)\b/g; /\bJava(\w*)\b/g reg.exec(text) (2) ["JavaScript", "Script", index: 0, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg.exec(text) (2) ["Java", "", index: 28, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg.exec(text) (2) ["JavaBeans", "Beans", index: 36, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg.exec(text) null reg.exec(text) (2) ["JavaScript", "Script", index: 0, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg = /\bJava(\w*)\b/; /\bJava(\w*)\b/ reg.exec(text) (2) ["JavaScript", "Script", index: 0, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg.exec(text) (2) ["JavaScript", "Script", index: 0, input: "JavaScript is more fun than Java or JavaBeans!", groups: undefined] reg = /^Java(\w*)/gm; /^Java(\w*)/gm reg.exec(text) (2) ["JavaScript", "Script", index: 0, input: "JavaScript is more fun than ↵Java or JavaBeans!", groups: undefined] reg.exec(text) (2) ["Java", "", index: 29, input: "JavaScript is more fun than ↵Java or JavaBeans!", groups: undefined] reg.exec(text) null
阻止事件发生
事件执行循序
自定义事件先执行：
大部分的都是自定义事件先执行，如a标签，subit
a:绑定事件后，会先执行自定义的事件，在进行跳转
默认事件先执行：
这种情况比较少，比如复选框（checkbox）
<body> <a id="l1" href="http://www.baidu.com">先弹出警告，再跳转</a> <input id="i1" type="checkbox"> <script src="jquery-3.2.1.min.js"></script> <script> document.getElementById('l1').onclick = function () { alert("我是先执行自定义事件") }; document.getElementById('i1').onclick = function () { //这里有两个事件，点击和不点击，不点击是默认事件，因为此时checkbox没有选择算是事件 console.log($("#i1").prop("checked")); }; </script> </body>