CODEWITHSUNDEEP
d3.js
Aleksandr Batsuev
Aleksandr Batsuev

Reputation: 161

d3js selection.each() callback group argument

Simple html:

 <div class="div1">
      <div class="test"><span>1</span></div>
      <div class="test"><span>2</span></div>
 </div>

And js:

var el = d3.select(".div1").selectAll(".test");
el.each(function() { 
      console.log(arguments);
});

Output:

[undefined, 0, 0]
[undefined, 1, 0]

What is the latest argument (0)? According to source code this is group, but I can't find anything about selector groups in d3 documentation.

Thanks.

Upvotes: 5

Views: 4070

Answers (1)

Aleksandr Batsuev
Aleksandr Batsuev

Reputation: 161

It's for nested selectors: http://bost.ocks.org/mike/nest/

e.g. for this HTML:

<table>
    <tr>
        <td></td>
        <td></td>
    </tr>
    <tr>
        <td></td>
        <td></td>
    </tr>
</table>

Let's select td:

var el = d3.selectAll("tr").selectAll("td");

el is [ Array[2] , Array[2] ]

and el.each:

el.each(function() { 
    console.log('args',arguments);
});

Output:

args [undefined, 0, 0]
args [undefined, 1, 0]
args [undefined, 0, 1]
args [undefined, 1, 1]

Upvotes: 6

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