Start time is less than end time Wdatepicker how this control is handled

The preceding date cannot be greater than the later date and two dates cannot be greater than the 2020-10-01 contract validity period from to <input id= "d4311" class= "wdate" type= "text" onfocus= "Wdatepicker" ({ MaxDate: ' #F {$dp. $D (\ ' d4312\ ') | | \ ' 2020-10-01\ '} '} '/> <input id= d4312 ' class= ' wdate ' type= ' text ' onfocus= ' Wdatepicker ({mindate: ' #F {$dp. $D (\ ' D4311\ ')} ', MaxDate: ' 2020-10-01 '} '/>

The preceding date cannot be greater than the following date
The validity of the contract is from
<input id= "d4311" class= wdate "type=" text "onfocus=" Wdatepicker ({maxdate: ' #F {$dp. $D (\ ' d4312\ ')} '}) "/>
<input id= "d4312" class= wdate "type=" text "onfocus=" Wdatepicker ({mindate: ' #F {$dp. $D (\ ' d4311\ ')} '}) "/>

Attention:
Two date formats must be the same

$DP. $ is equivalent to the document.getElementById function.
So why is it inside the ' use '? That is because "and" are used by the peripheral functions, so use the escape character \, otherwise you will be prompted JS syntax errors.
So when you use it elsewhere, be careful to use the ' change ' or ' to '.

#F {$dp. $D (\ ' d4312\ ') | | \ ' 2020-10-01\ '} indicates that the 2020-10-01 value is used as the maximum value when d4312 is empty