默认情况下，单选按钮不显示为选中.我开始时没有默认选择，做了一些非常简单的 js 验证，但它不起作用.所以我选择只使用默认值，直到我弄清楚并发现发生了一些奇怪的事情.

The radio button does not show up as checked by default. I started off without a default choice doing some very simple js validation and it wasn't working. So I opted to just use default values until I figured that out and discovered that something weird is going on.

标记是有效的，我已经在 FF、Safari 和 Chrome 中尝试过.没有任何效果.

The markup is valid and I've tried in FF, Safari and Chrome. Nothing works.

我认为这是与 jQuery 库的冲突，因为当我删除调用脚本时问题就消失了.

I think it's a conflict with the jQuery library because the problem goes away when I remove the call script.

<label>Do you want to accept American Express?</label> Yes
<input id="amex" style="width: 20px;" type='radio' name='Contact0_AmericanExpress' value='1' /> No
<input style="width: 20px;" type='radio' name='Contact0_AmericanExpress' class='check' value='0' checked="checked" />

推荐答案

如果你有多个同名的属性为 checked 属性，它将采用页面上最后一个选中的单选.

If you have multiple of the same name with the checked attribute it will take the last checked radio on the page.

<form>
    <label>Do you want to accept American Express?</label>
    Yes<input id="amex" style="width: 20px;" type="radio" name="Contact0_AmericanExpress"  />  
    maybe<input id="amex" style="width: 20px;" type="radio" name="Contact0_AmericanExpress"  checked="checked" />  
    No<input style="width: 20px;" type="radio" name="Contact0_AmericanExpress" class="check" checked="checked" />
</form>