使用preventDefault和提交表单的困难

时间：2013-02-08 00:36:57

标签： javascript html form-submit preventdefault

我正在使用动态表格。当我在第一个文本字段中输入我的名字，然后按回车键，弹出下一个文本字段，请求我的电子邮件。但是，我可以点击输入多次，下一个文本字段不断弹出，我只想弹出一次。另一个问题是，我的下一个文本字段，请求我的电子邮件，如果我按两次输入提交表单，我也想阻止。任何解决方案？

Javascript 

function addEvent(element, eventType, theFunction, capture) {
if (element.addEventListener) {
    element.addEventListener(eventType, theFunction, capture);
}
else if (element.attachEvent) {
    element.attachEvent("on" + eventType, theFunction);
}
}


function createEmailField() {
if ((window.event && window.event.keyCode == 13) || event.keyCode == 13) {

    var name = document.getElementById("name").value;

    if (name == "") {
        window.alert("Mata in ditt namn");
    }
    else if (name.search(/^[A-Za-z]+$/) == -1) {
        window.alert("Mata in ett namn med bokstäver");
    }
    else {

        var newDiv = document.createElement("div");

        var br = document.createElement("br");
        newDiv.appendChild(br);

        newDiv.appendChild(document.createTextNode("Hej " + name + "!"));

        var br = document.createElement("br");
        newDiv.appendChild(br);

        newDiv.appendChild(document.createTextNode("Hur når vi dig?"));

        var br = document.createElement("br");
        newDiv.appendChild(br);

        newDiv.appendChild(document.createTextNode("Epost:"));

        var br = document.createElement("br");
        newDiv.appendChild(br);

        var input = document.createElement("input");
        input.setAttribute("type", "text");
        input.setAttribute("id", "email");
        input.setAttribute("name", "email");
        newDiv.appendChild(input);

        var form = document.getElementById("form");
        form.appendChild(newDiv);

        var email = document.getElementById("email");
        addEvent(email, "change", createTextArea, false);

    }
}
}

function createTextArea() {

var email = document.getElementById("email").value;

if (email == "") {
    alert("Mata in ditt email");
}
else if (email.search(/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/) == -1) {
    window.alert("Mata in ett korrekt email");
}
else {
    var newDiv = document.createElement("div");

    var br = document.createElement("br");
    newDiv.appendChild(br);

    newDiv.appendChild(document.createTextNode("Vad har du för fråga om vår verksamhet?"));

    var br = document.createElement("br");
    newDiv.appendChild(br);

    var textArea = document.createElement("textArea");
    textArea.setAttribute("id", "question");
    textArea.setAttribute("name", "question");
    textArea.cols = "30";
    textArea.rows = "5";
    newDiv.appendChild(textArea);

    var br = document.createElement("br");
    newDiv.appendChild(br);

    newDiv.appendChild(document.createTextNode("Vi kommer att svara dig via: " +   email));

    var br = document.createElement("br");
    newDiv.appendChild(br);

    var button = document.createElement("input");
    button.setAttribute("type", "submit");
    button.setAttribute("value", "Skicka");
    button.setAttribute("name", "Skicka");
    button.setAttribute("id", "submit");
    newDiv.appendChild(button);

    var form = document.getElementById("form");
    form.appendChild(newDiv);

}
}

function prevent(event) {
if ((window.event && window.event.keyCode == 13) || event.keyCode == 13) {
    if (window.event) {
        window.event.returnValue = false;
    } else if (event.preventDefault) {
        event.preventDefault();
    }
}
}


function init() {
var name = document.getElementById("name");
addEvent(name, "keyup", createEmailField, false);
name.onkeypress = prevent;
}

window.onload = init;

HTML 

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

<html>

<head>
<title>Inl1-3</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<script type="text/javascript" src="Uppg3.js" >
</script>

</head>

<body>

<h2> Frågeformulär </h2>
<form id="form" method="post"     action="http://student.ts.mah.se/da123aht11/echoscript.php">
<div>
    Vad heter du?... 
    <br /><input type="text" name="name" id="name" /> 
</div>
</form>


</body>

</html>

2 个答案:

答案 0 :(得分：1)

解决方案是保留状态变量以检查电子邮件字段/文本区域是否像var emailCreated = false, textareaCreated = false;一样创建并检查状态并在操作完成后更新它们。

function addEvent(element, eventType, theFunction, capture) {
if (element.addEventListener) {
    element.addEventListener(eventType, theFunction, capture);
}
else if (element.attachEvent) {
    element.attachEvent("on" + eventType, theFunction);
}
}


function createEmailField() {
if ((window.event && window.event.keyCode == 13) || event.keyCode == 13) {
    if(emailCreated){
        return;
    }

    var name = document.getElementById("name").value;

    if (name == "") {
        window.alert("Mata in ditt namn");
    }
    else if (name.search(/^[A-Za-z]+$/) == -1) {
        window.alert("Mata in ett namn med bokstäver");
    }
    else {

        var newDiv = document.createElement("div");

        var br = document.createElement("br");
        newDiv.appendChild(br);

        newDiv.appendChild(document.createTextNode("Hej " + name + "!"));

        var br = document.createElement("br");
        newDiv.appendChild(br);

        newDiv.appendChild(document.createTextNode("Hur når vi dig?"));

        var br = document.createElement("br");
        newDiv.appendChild(br);

        newDiv.appendChild(document.createTextNode("Epost:"));

        var br = document.createElement("br");
        newDiv.appendChild(br);

        var input = document.createElement("input");
        input.setAttribute("type", "text");
        input.setAttribute("id", "email");
        input.setAttribute("name", "email");
        newDiv.appendChild(input);

        var form = document.getElementById("form");
        form.appendChild(newDiv);

        var email = document.getElementById("email");
        addEvent(email, "change", createTextArea, false);

        emailCreated = true;

    }
}
}

function createTextArea() {
    if(textareaCreated){
        return;
    }

var email = document.getElementById("email").value;

if (email == "") {
    alert("Mata in ditt email");
}
else if (email.search(/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/) == -1) {
    window.alert("Mata in ett korrekt email");
}
else {
    var newDiv = document.createElement("div");

    var br = document.createElement("br");
    newDiv.appendChild(br);

    newDiv.appendChild(document.createTextNode("Vad har du för fråga om vår verksamhet?"));

    var br = document.createElement("br");
    newDiv.appendChild(br);

    var textArea = document.createElement("textArea");
    textArea.setAttribute("id", "question");
    textArea.setAttribute("name", "question");
    textArea.cols = "30";
    textArea.rows = "5";
    newDiv.appendChild(textArea);

    var br = document.createElement("br");
    newDiv.appendChild(br);

    newDiv.appendChild(document.createTextNode("Vi kommer att svara dig via: " +   email));

    var br = document.createElement("br");
    newDiv.appendChild(br);

    var button = document.createElement("input");
    button.setAttribute("type", "submit");
    button.setAttribute("value", "Skicka");
    button.setAttribute("name", "Skicka");
    button.setAttribute("id", "submit");
    newDiv.appendChild(button);

    var form = document.getElementById("form");
    form.appendChild(newDiv);

    textareaCreated = true;

}
}

function prevent(event) {
if ((window.event && window.event.keyCode == 13) || event.keyCode == 13) {
    if (window.event) {
        window.event.returnValue = false;
    } else if (event.preventDefault) {
        event.preventDefault();
    }
}
}


function init() {
var name = document.getElementById("name");
addEvent(name, "keyup", createEmailField, false);
name.onkeypress = prevent;
}


var emailCreated = false, textareaCreated = false;
window.onload = init;

演示：Fiddle

另一种方法是使用removeEvent()函数

function removeEvent(element, eventType, theFunction, capture) {
if (element.removeEventListener) {
    element.removeEventListener(eventType, theFunction, capture);
}
else if (element.detachEvent) {
    element.detachEvent("on" + eventType, theFunction);
}
}

分别在添加电子邮件字段和textarea后调用removeEvent(document.getElementById("name"), "keyup", createEmailField, false);和removeEvent(document.getElementById("email"), "change", createTextArea, false);。

答案 1 :(得分：0)

在创建电子邮件字段后，您似乎没有删除事件侦听器，因此它仍处于活动状态。创建第二个字段后，需要从第一个字段中删除事件侦听器。

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