Uncaught TypeError in javascript function

Question

Storage.prototype.setObj = function(key, obj) {
    return this.setItem(key, JSON.stringify(obj))
    ^-----Error in this line: Uncaught TypeError: Accessing selectionDirection on an input element that cannot have a selection
}
var selected = jQuery('input:checkbox.mychkbox:checked').each(function() {
        return this.id;
});
sessionStorage.setObj("savedCollSearch",selected);

I am using jQuery 1.7.2 and Chrome 22. This error shows up as Uncaught Exception in Firefox 16. Search in SO and Google does not help and I have no clue how to resolve this.

I am 100% sure jQuery is loaded properly.

@raina77ow: you should read this: developer.mozilla.org/en-US/docs/DOM/Storage — exception
– exception, Commented Oct 16, 2012 at 14:44
@raina77ow: Well, you got me there :-P It just bugs me a little when people say "json object", it's a "JavaScript object". JSON is a string representation of data that happens to resemble JavaScript object syntax. — gen_Eric
– gen_Eric, Commented Oct 16, 2012 at 15:25

raina77ow · Accepted Answer · 2012-10-16 15:02:38Z

4

This expression...

var selected = jQuery('input:checkbox.mychkbox:checked').each(function() {
  return this.id;
});

... seems to be misused here: it'll return you a jQuery-wrapped collection of checked checkbox elements, which is probably not quite easy to stringify (because of circular references).

(as a sidenote, .each will stop the iteration at the first element which doesn't have an id, or have it set to an empty string, but that doesn't matter much here)

You probably wanted to use this instead:

var selected = jQuery('input:checkbox.mychkbox:checked').map(function() {
  return this.id;
}).get();

answered Oct 16, 2012 at 15:02

raina77ow

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4 Comments

exception Over a year ago

I had it as map instead of each, until I read here:stackoverflow.com/a/749119/1446848 that map is more memory intensive than each. Can you point me to some documentation on "circular references". Never heard of that before in javascript.

gen_Eric Over a year ago

@exception: map and each are different functions used for different purposes. Use the correct one for what you are doing, stop the micro-optimizations! One may be more "memory intensive", but unless you have like 1,000,000 elements, it doesn't matter.

raina77ow Over a year ago

@exception Why, there's a whole lot of such questions here at SO. Even a special tag for that. )

raina77ow Over a year ago

@exception Of course, it's memory intensive - map is used to return a collection, so it has to store the result somewhere. ) each, on the other side, usually just does something for each element of collection.

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