1, if the form is only one input field, then press enter trigger input form submit
2, if there are two or more form more input fields, but no buttons or input [type = submit], press enter in the input form does not trigger Submit
3, if there is a form or a plurality of input fields, and have one or more buttons or input [type = submit], in the input and press the enter button or trigger a first input [type = submit] Click process procedures, and triggers a commit processing program on the enclosed form