初学JavaScript常用函数(五)

来源：互联网发布：js encodeuri 两次编辑：程序博客网时间：2024/05/16 00:42

JavaScript常用函数包括JavaScript全局函数和JavaScript window对象常用的方法及事件。JavaScript全局函数有7个，分别为：escape()函数、eval()函数、isNan()函数、ifFinite()函数、parseInt()函数、parseFloat()函数、unescape()函数、Eval()函数。

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>JS中常用函数</title></head><body><script type="text/javascript">document.write("escape() 函数可对字符串进行编码，这样就可以在所有的计算机上读取该字符串<br>");var str="escape%28%29%u662F%u5BF9%u5B57%u7B26%u4E32%u8FDB%u884C%u7F16%u7801%21";var str1 = "escape()是对字符串进行编码!";var str2 = "+-1*$%^";var str3 = "+-1*%24%25%5E";document.write(unescape(str)+"<br/>")document.write(escape(str1)+"<br/>");document.write(unescape(str2)+"<br/>");document.write(unescape(str3)+"<br/>");document.write("eval() 函数可计算某个字符串，并执行其中的的 JavaScript 代码。<br/>")eval("x=20;y=10;document.write(x*y)");document.write("<br/>");document.write(eval("2+2"));document.write("<br/>");var str = 10;document.write(eval(str+10)+"<br/>");document.write("isNaN() 函数用于检查其参数是否是非数字值<br/>")document.write(isNaN(123)+"<br/>");document.write(isNaN(-1.23)+"<br/>");document.write(isNaN(5-2)+"<br/>");document.write(isNaN(0)+"<br/>");document.write(isNaN("hello")+"<br/>");document.write(isNaN("1+2")+"<br/>");//isFinite() 函数用于检查其参数是否是无穷大//如果 number 是有限数字（或可转换为有限数字），那么返回 true。否则，如果 number 是 NaN（非数字），//或者是正、负无穷大的数，则返回 false。document.write(isFinite(123)+ "<br />")document.write(isFinite(-1.23)+ "<br />")document.write(isFinite(5-2)+ "<br />")document.write(isFinite(0)+ "<br />")document.write(isFinite("Hello")+ "<br />")document.write(isFinite("2005/12/12")+ "<br />")//parseFloat() 函数可解析一个字符串，并返回一个浮点数。//该函数指定字符串中的首个字符是否是数字。如果是，则对字符串进行解析，//直到到达数字的末端为止，然后以数字返回该数字，而不是作为字符串。document.write(parseFloat("10")+"<br/>");document.write(parseFloat("10.00")+"<br/>") ;document.write(parseFloat("10.33")+"<br/>") ;document.write(parseFloat("34 45 66")+"<br/>"); document.write(parseFloat(" 60 ")+"<br/>") ;document.write(parseFloat("40 years")+"<br/>");document.write(parseFloat("He was 40")+"<br/>");//parseInt() 函数可解析一个字符串，并返回一个整数。document.write(parseInt("10")+"<br/>");//返回 10document.write(parseInt("19",10)+"<br/>");//返回 19 (10+9)document.write(parseInt("11",2)+"<br/>");//返回 3 (2+1)document.write(parseInt("17",8)+"<br/>");//返回 15 (8+7)document.write(parseInt("1f",16)+"<br/>");//返回 31 (16+15)document.write(parseInt("010")+"<br/>");//未定：返回 10 或 8</script></body></html>

JavaScript window对象中常用的方法及事件：

alert()方法：

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>JavaScript Window对象常用的方法及事件-alert()</title><script type="text/javascript">//window可以省略window.alert("window对象alert()方法");</script></head><body></body></html>

confirm()方法：

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>JavaScript对象confirm()方法</title><script type="text/javascript">function func1(){var x = window.confirm("点击确定按钮");if(x==true){x = "你点击了确定按钮";}else{x = "你点击了取消按钮";}document.getElementById("demo1").innerHTML=x;}</script></head><body><button onclick="func1()">点我</button><p id="demo1"></p></body></html>

prompt()方法

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>JavaScript对象prompt()方法</title><script type="text/javascript">function fun1(){var x;var person = window.prompt("请输入你的名字:", "PeterPan");if(!person!=null && person!=""){x="你好,"+person+":新年快乐!"document.getElementById("demo").innerHTML=x;}}</script></head><body><input type="button" value="点我" onclick="fun1()"/><p id="demo"></p></body></html>

JavaScript对象setTimeout()方法

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>JavaScript对象setTimeout()方法</title><script type="text/javascript">function func1(){setTimeout(function(){alert("Hello,happy new year!")}, 5000);}function func2(){alert("新年快乐!");}window.setTimeout("func2()", 3000);</script></head><body><p>点击按钮，将在5秒钟出现提示。</p><button onclick="func1()">点击我</button></body></html>

JavaScript对象setInterval()方法

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>JavaScript对象setInterval()方法</title><script type="text/javascript">function fun1(){var date = new Date();var year = date.getFullYear();var month = date.getMonth()+1;var day = date.getDate();var hour = date.getHours();var minute = date.getMinutes();var second = date.getSeconds();var week = date.getDay();switch(week){case 0: week = "周日"; break;case 1: week = "周一"; break;case 2: week = "周二"; break;case 3: week = "周三"; break;case 4: week = "周四"; break;case 5: week = "周五"; break;case 6: week = "周六"; break;default: week="逆天了!"; break;}var time = year+"年  "+month+"月  "+day+"日  "+week+" "+hour+"时  "+minute+"分  "+second+"秒";document.getElementById("day1").innerHTML=time;}window.setInterval("fun1()", 1000);</script></head><body><p id="day1"></p></body></html>

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>JavaScript对象setInterval()方法</title><script type="text/javascript">function func1(){var date = new Date();var t = date.toLocaleTimeString();document.getElementById("clock").value=t;}var time1 = window.setInterval("func1()", 1000);</script></head><body><input type="text" id="clock" name="click"/><button onclick="window.clearInterval(time1)">停止</button></body></html>

JavaScript对象open()方法

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>JavaScript对象open()方法</title><script type="text/javascript">function fun1(){window.open("http://www.baidu.com");}</script></head><body><button onclick="fun1()">点我进百度</button></body></html>

JavaScript对象onload()方法

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>JavaScript对象onload方法()</title><script type="text/javascript">/*window.onload=function(){alert("文档加载完毕!");}*/function init(){alert("文档加载完毕!");}</script></head><body onload="init()"></body></html>

JavaScript对象onresize()方法

<!DOCTYPE html><html><head><meta charset="UTF-8"><title>JavaScript对象onresize()方法</title><script type="text/javascript">window.onresize = function(){alert("窗口发生变化!");}</script></head><body></body></html>

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