This is particularly handy when working with forms and validations, and you will likely use these functions quite often when creating interactive Web sites with form elements.

在处理表单和验证时，这一点尤其便利，而且在用Form元素创建交互web站点时更有可能会用到这些函数。

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Dynamic interactions. The dynamic features vary from interactive, human edited forms with dynamic calculations, validations, and other events to server-generated, machine-filled forms.

动态功能从具有动态计算、验证及其他特性的交互式、可编辑的表单，到服务器生成的、机器填充的表单等各不相同。

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