post/get 提交form中的数据会刷新页面！

刚刚学php，前端更是迷惑...

<form acton="index.php" method = "post">

<input type="input" id = "username" name="username"  placeholder="请输入" />

<input type="input" id = "email" name="email"  placeholder="请输入" />

<input type="submit" id="submitit"  value =" 提交" />

</form>

<script>

$(document).ready(function(){

$("#submit").click(function() {

var email = $("#email").val();

var username = $("#username").val();

$.ajax({

'type' :"POST",

‘url':'index.php'

‘dataType’ : 'json',

'data' : '{'username': username,'email' : email }'

..........

})

});

});

</script>

//////////////////////////////会重复提交form中的内容的，后来改为下面的了

<input type="input" id = "username" name="username"  placeholder="请输入" />

<input type="input" id = "email" name="email"  placeholder="请输入" />

<input type="submit" id="submitit"  value =" 提交" />

<script>

$(document).ready(function(){

$("#submit").click(function() {

var email = $("#email").val();

var username = $("#username").val();

$.ajax({

'type' :"POST",

‘url':'index.php'

‘dataType’ : 'json',

'data' : '{'username': username,'email' : email }'

..........

})

});

});

</script>