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Re: cloneNode

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JJ wrote:

> On Tue, 8 Aug 2017 12:25:50 -0700 (PDT), justaguy wrote:
>> I wonder if there's any way such as inserting a new element with id to a
>> cloned node?  Thus, to be able to differentiate them.
> 
> Yes. Just assign a new unique ID to the new element after it's created. It
> might be good to use randomly generated ID. e.g.
> 
>   var newID = ("button_" + (new Date()).valueOf()) +
>               Math.trunc(Math.random() * 1000000);
> 
> You might want to keep track of the IDs in an array so that you can access
> that new element. Or better, keep the element reference rather than its
> ID.

The built-in `Date` prototype method that should be called here is 
`getTime`, not `valueOf`, although both return (and have always returned) 
the same value.

<http://www.ecma-international.org/ecma-262/7.0/#sec-date.prototype.valueof>

vs.

<http://www.ecma-international.org/ecma-262/7.0/#sec-date.prototype.gettime>

The `Math` object has a built-in `trunc` method only in newer ECMAScript 
implementations.  Therefore, the methods used to produce a uniformly 
distributed pseudo-random integer should be `floor` or `ceil`:

<http://www.ecma-international.org/ecma-262/7.0/#sec-math-object>

vs.

<http://www.ecma-international.org/ecma-262/5.1/#sec-15.8>

As one can see there, the advantages of calling the `trunc` method instead 
of the `floor` method are negligible; the disadvantages are important.

“1e6” might be easier to read than “1000000”.

However, it is much better *here* not to rely on either value, but to use a 
custom counter (if that; I can only think of separate `label` elements in 
siblings as a valid reason).  If all elements have the same name, but should 
have different IDs, the current counter value is easily obtained through the 
`length` property of the corresponding HTMLCollection.  For 1-based 
counting:

  /*
   * Makes `newID` “button_4” if there are already 3 controls named
   * “button” in the form represented by the object referred to by `f`
   */
  var newID = "button_" + (f.elements["button"].length + 1);

    [The ID prefix does not have to be the same as the name.]

-- 
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cloneNode justaguy <lichunshen84@gmail.com> - 2017-08-08 12:25 -0700
  Re: cloneNode "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2017-08-09 16:04 +0200
  Re: cloneNode JJ <jj4public@vfemail.net> - 2017-08-09 23:26 +0700
    Re: cloneNode Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-08-09 23:43 +0200
    Re: cloneNode justaguy <lichunshen84@gmail.com> - 2017-08-09 18:48 -0700

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