JavaScript之实例

时间：2025-03-04 14:34:32
  <meta charset="UTF-8">

  <meta http-equiv="x-ua-compatible" content="IE=edge">

  <meta name="viewport" content="width=device-width, initial-scale=1">

  <title>定时器</title>

  <script>

    var intervalId;

    function f() {

      var timeStr = (new Date()).toLocaleString();

      var inputEle = document.getElementById("i1");

      inputEle.value = timeStr;

    }

    function start() {

      f();

      if (intervalId === undefined) {

        intervalId = setInterval(f, );

      }

    }

    function end() {

      clearInterval(intervalId);

      intervalId = undefined;

    }

  </script>

</head>

<body>

<input type="text" id="i1">

<input type="button" value="开始" id="start" onclick="start();">

<input type="button" value="结束" id="end" onclick="end();">

</body>

</html>

刷新时间

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>搜索框示例</title>

</head>

<body>

    <input id="d1" type="text" value="请输入关键字" onblur="blurs()" onfocus="focus()">

<script>

function focus(){

    var inputEle=document.getElementById("d1");

    if (inputEle.value==="请输入关键字"){

        inputEle.value="";

    }

}

function blurs(){

    var inputEle=document.getElementById("d1");

    var val=inputEle.value;

    if(!val.trim()){

        inputEle.value="请输入关键字";

    }

}

</script>

</body>

</html>

搜索框

<!DOCTYPE html>

<html lang="zh-CN">

<head>

  <meta charset="UTF-8">

  <meta http-equiv="x-ua-compatible" content="IE=edge">

  <meta name="viewport" content="width=device-width, initial-scale=1">

  <title>select联动</title>

</head>

<body>

<select id="province">

  <option>请选择省:</option>

</select>

<select id="city">

  <option>请选择市:</option>

</select>

<script>

  data = {"河北省": ["廊坊", "邯郸"], "北京": ["朝阳区", "海淀区"], "山东": ["威海市", "烟台市"]};

  var p = document.getElementById("province");

  var c = document.getElementById("city");

  for (var i in data) {

    var optionP = document.createElement("option");

    optionP.innerHTML = i;

    p.appendChild(optionP);

  }

  p.onchange = function () {

    var pro = (this.options[this.selectedIndex]).innerHTML;

    var citys = data[pro];

    // 清空option

    c.options.length = ;

    for (var i=;i<citys.length;i++) {

      var option_city = document.createElement("option");

      option_city.innerHTML = citys[i];

      c.appendChild(option_city);

    }

  }

</script>

</body>

</html>

select联动菜单

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