常用的 Javascript 操作汇总 (五)

45 动态复制文本框内容 1: <form name=”myForm”> 2: Enter some Text: <input type=”text” name=”myText”><br> 3: Copy Text: <input type=”text” name=”copyText”> 4: </form> 5: <a href=”#” onClick=”document.myForm.copyText.value = 6: document.myForm.myText.value;”>Copy Text Field</a> 46 侦测文本框的变化 1: <form name=”myForm”> 2: Enter some Text: <input type=”text” name=”myText” onChange=”alert(this.value);”> 3: </form> 47 访问选中的Select 1: <form name=”myForm”> 2: <select name=”mySelect”> 3: <option value=”First Choice”>1</option> 4: <option value=”Second Choice”>2</option> 5: <option value=”Third Choice”>3</option> 6: </select> 7: </form> 8: <a href='#' onClick='alert(document.myForm.mySelect.value);'>Check Selection List</a> 48 动态增加Select项 1: <form name=”myForm”> 2: <select name=”mySelect”> 3: <option value=”First Choice”>1</option> 4: <option value=”Second Choice”>2</option> 5: </select> 6: </form> 7: <script language=”JavaScript”> 8: document.myForm.mySelect.length++; 9: document.myForm.mySelect.options[document.myForm.mySelect.length - 1].text = “3”; 10: document.myForm.mySelect.options[document.myForm.mySelect.length - 1].value = “Third Choice”; 11: </script> 49 验证表单字段 1: <script language=”JavaScript”> 2: function checkField(field) { 3: if (field.value == “”) { 4: window.alert(“You must enter a value in the field”); 5: field.focus(); 6: } 7: } 8: </script> 9: <form name=”myForm” action=”target.html”> 10: Text Field: <input type=”text” name=”myField”onBlur=”checkField(this)”> 11: <br><input type=”submit”> 12: </form> 50 验证Select项 1: function checkList(selection) { 2: if (selection.length == 0) { 3: window.alert(“You must make a selection from the list.”); 4: return false; 5: } 6: return true; 7: } 51 动态改变表单的action 1: <form name=”myForm” action=”login.html”> 2: Username: <input type=”text” name=”username”><br> 3: Password: <input type=”password” name=”password”><br> 4: <input type=”button” value=”Login” onClick=”this.form.submit();”> 5: <input type=”button” value=”Register” onClick=”this.form.action = ‘register.html’; this.form.submit();”> 6: <input type=”button” value=”Retrieve Password” onClick=”this.form.action = ‘password.html’; this.form.submit();”> 7: </form> 52 使用图像按钮 1: <form name=”myForm” action=”login.html”> 2: Username: <input type=”text” name=”username”><br> 3: Password: <input type=”password”name=”password”><br> 4: <input type=”image” src="/”login.gif"” value=”Login”> 5: </form> 6: