jQuery each - combining (this) with class specification

问题:

I'm trying to cycle through some table rows. The simplified rows are as follows:

<table>   <tr id="ucf48">     <td class="ucf_text">       <input name="ucf_t48" value="Ann becomes very involved in the text she is reading." type="text">     </td>   </tr>   <tr id="ucf351">     <td class="ucf_text">       <input name="ucf_t351" value="Ann is a fast and confident reader." type="text">     </td>   </tr> </table> 

I'm using this code to cycle:

$('#ucf tr').each(function(i,obj){     var cn=$(this).attr('id').substr(3);     var t=$(this +'.ucf_text input').val();      console.log("Row "+i);     console.log("Cnum: "+cn);     console.log(t); }); 

The console output is:

Row 0 Cnum: 48 Ann becomes very involved in the text she is reading. Row 1 Cnum: 351 Ann becomes very involved in the text she is reading. 

Now before someone flames me, I know I can do this another way by referring to the data I want using 'name'. Why, however, does my cnum variable follow 'this' but the t variable does not?

Thanks.

回答1:

When you do:

var t=$(this +'.ucf_text input').val(); 

this isn't converting correctly to a string.

Try:

var t=$(this).find('.ucf_text input').val(); 

回答2:

var t=$(this +'.ucf_text input').val();

You're trying to concatenate a string with a DOM node. I assume you want the children of each row? Which would be:
var t=$(this).find('.ucf_text input').val();

回答3:

You cannot concatenate DOM objects and strings.

You can easily fix this by specifying this as the context of the selector:

var t = $('.ucf_text input', this).val(); 

By doing so the selector only matches elements inside the given context, i.e. the table row in your case.

回答4:

You've already got 2 correct answers, but just for the sake of diversity, here's another way to do it:

var t = $('.ucf_text input', this).val();

回答5:

Actually, this is because $(this) [tr] doesn't have the class .ucf_text

I think you meant the td beneath it

Add a space to signify you mean the child. :)

var t=$(this +' .ucf_text input').val();                ^ Space! 

EDIT: Or not!

var t=$(this).children('.ucf_text').children('input').val(); 

Find is way cooler, but I'm editing for the sake of not leaving a wrong answer up and wanted to be somewhat original, and besides... Maybe you need a distinct path to the input?

文章来源: jQuery each - combining (this) with class specification