Tip：這個e.detail.fromId，就是formid，真機才會產生，模擬器中為“the formId is a mock one”

wxml佈局

<form bindsubmit="goto_index" report-submit="true">
    <button class="form_button" form-type="submit">
        <image src="../../img/tx.jpeg" mode="aspectFit" ></image>
    </button>
</form
 
>

清除button預設樣式，通用

button.form_button{background-color:transparent;padding:0;margin:0;display:inline;position:static;border:0;padding-left:0;padding-right:0;border-radius:0;font-size:0rpx;color:transparent;}

button.form_button::after{content:'';width:0;height:0;-webkit-transform:scale(1);transform:scale(1
 
);display:none;background-color:transparent;}

js

goto_index:function(e){
  //獲取點選formid
  console.log(e.detail.formId)
}