对于Select2 Jquery问题

这个问题是由于HTML5验证不能聚焦隐藏的无效元素。 我在处理jQuery Select2插件时遇到了这个问题。

解决方案 你可以在表单的每个元素上注入事件监听器和“无效”事件，这样你就可以在HTML5验证事件之前进行操作。

$('form select').each(function(i){
this.addEventListener('invalid', function(e){            
        var _s2Id = 's2id_'+e.target.id; //s2 autosuggest html ul li element id
        var _posS2 = $('#'+_s2Id).position();
        //get the current position of respective select2
        $('#'+_s2Id+' ul').addClass('_invalid'); //add this class with border:1px solid red;
        //this will reposition the hidden select2 just behind the actual select2 autosuggest field with z-index = -1
        $('#'+e.target.id).attr('style','display:block !important;position:absolute;z-index:-1;top:'+(_posS2.top-$('#'+_s2Id).outerHeight()-24)+'px;left:'+(_posS2.left-($('#'+_s2Id).width()/2))+'px;');
        /*
        //Adjust the left and top position accordingly 
        */
        //remove invalid class after 3 seconds
        setTimeout(function(){
            $('#'+_s2Id+' ul').removeClass('_invalid');
        },3000);            
        return true;
}, false);          
});

前面的答案都不适合我，而且我没有任何具有必需属性的隐藏字段。

在我的例子中，问题是由于有一个<form>和一个<fieldset>作为它的第一个子元素，它包含了具有所需属性的<input>。删除<fieldset>解决了这个问题。或者你可以用它来包装你的表单;HTML5是允许的。

我使用的是Windows 7 x64, Chrome版本43.0.2357.130 m。

这个问题发生在Chrome上，如果一个表单字段验证失败，但由于各自的无效控件无法聚焦，浏览器试图显示消息“请填写此字段”旁边也失败了。

由于多种原因，表单控件在触发验证时可能无法聚焦。下面描述的两种情况是最突出的原因:

The field is irrelevant according to the current context of the business logic. In such a scenario, the respective control should be disabled or removed from the DOM or not be marked with the required attribute at that point. Premature validation may occur due to a user pressing ENTER key on an input. Or a user clicking on a button/input control in the form which has not defined the type attribute of the control correctly. If the type attribute of a button is not set to button, Chrome (or any other browser for that matter) performs a validation each time the button is clicked because submit is the default value of a button's type attribute.

为了解决这个问题，如果你的页面上有一个按钮是做其他事情而不是提交或重置，请记住这样做:<button type="button">。

在表单中添加novalidate属性将有助于:

<form name="myform" novalidate>

以防其他人有这个问题，我也经历过同样的事情。正如评论中所讨论的，这是由于浏览器试图验证隐藏字段。它在表单中寻找空字段并试图集中在它们上，但是因为它们被设置为display:none;，所以它不能。因此出现了错误。

我可以用类似的方法来解决这个问题:

$("body").on("submit", ".myForm", function(evt) {

    // Disable things that we don't want to validate.
    $(["input:hidden, textarea:hidden, select:hidden"]).attr("disabled", true);

    // If HTML5 Validation is available let it run. Otherwise prevent default.
    if (this.el.checkValidity && !this.el.checkValidity()) {
        // Re-enable things that we previously disabled.
        $(["input:hidden, textarea:hidden, select:hidden"]).attr("disabled", false);
        return true;
    }
    evt.preventDefault();

    // Re-enable things that we previously disabled.
    $(["input:hidden, textarea:hidden, select:hidden"]).attr("disabled", false);

    // Whatever other form processing stuff goes here.
});

此外，这可能是重复的“无效的窗体控件”只有在谷歌Chrome

使用ElementInternals API的自定义元素元素不能使用delegatesFocus: true与shadowRoot，因为元素必须直接接收焦点(目前，这可能会发展)在公开的表单的DOM树(父表单可以在shadowRoot，它只是必须在同一部分的树与自定义和其他表单元素);元素必须是可见的，在我的实验中tabindex=0是必需的元素(-1似乎也工作)

一个从googlchrome扩展的带有自定义元素的演示在https://jimmont.github.io/samples/report-validity/

the error is simply reporting that an element which has attributes indicating it needs validation cannot receive focus when there's a problem with the validation, so the user can correct the error; if the error and information is coming in as expected you can ignore the error; otherwise it's likely the result of some UI features hiding elements and a mix of unexpected behavior; it's possible to use another approach in implementations to allow the user to walk back through a flow of some sort, but it appears that's beyond the scope of the question at the moment