form表单下的按钮在没有指定type类型的时候，如果我们同时给其添加了点击事件的话。会发现我们在点击的时候回默认的把表单也给提交了。如：
<script type="text/javascript"> function validate(){ alert("test"); }</script><button id="validate" onclick="validate();"></button> 于是我大胆猜测应该是form下的button 按钮在没有明确的给出type类型时，会有一个默认值为：type=”submit”.
带着这种猜测于是开始查找资料，在：https://www.w3.org/TR/2011/WD-html5-20110525/the-button-element.html#attr-button-type验证了我的猜测：
The type attribute controls the behavior of the button when it is activated. It is an enumerated attribute. The following table lists the keywords and states for the attribute — the keywords in the left column map to the states in the cell in the second column on the same row as the keyword.Keyword State Brief descriptionsubmit Submit Button Submits the form.reset Reset Button Resets the form.button Button Does nothing.**The missing value default is the Submit Button state.** 截图： 
解决办法很明显了：如果该按钮的作用不是为了提交表单的话，我们给其加上type属性就行了：
<button id="validate" type="button" onclick="validate();"></button>