Add count as property to javascript object

Question

I have two arrays:

one with categories
one with datarecords

Every data record belongs to a specific category.

With every use of a filter (e.g. searchfield) on the datarecords, I want to add the total count of records per category to each category-object, so I can display them on every tab-pane (e.g. text: Algemeen, value: 'general, countFiltered: 2)

I made a fiddle for this.

Till now I get no count-filtered, locally I get a constant error corresponding to line 78 in my fiddle:

Uncaught (in promise) Type Error: Cannot read property '0' of undefined

How can I achieve this?

I think the question actually makes sense, you just have to read it slower. When he searches he wants the number of results for each category to show up on the pane of that category, kind of like a facebook badge. — zfrisch
– zfrisch, Commented Jan 5, 2016 at 20:40

Paul · Accepted Answer · 2016-01-05 20:35:34Z

7

this isn't what you think it is here:

var filtered = results.filter(function (results) {
    return (results.category.toLowerCase() == this.categories[cat].value.toLowerCase());
});

You can either pass in a thisArg to filter:

var filtered = results.filter(function (results) {
    return (results.category.toLowerCase() == this.categories[cat].value.toLowerCase());
}, this);

or in ES6 you can use an arrow function:

var filtered = results.filter(
    results => results.category.toLowerCase() == this.categories[cat].value.toLowerCase() 
);

answered Jan 5, 2016 at 20:35

Paul

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5 Comments

bflydesign Over a year ago

Solved it! Why do you need to pass a thisArg? Does it apply to the results in my vue-model?

Paul Over a year ago

@BFlyDesign A closure has access to outer-scoped variables only if they aren't shadowed by it's own variables, but every time a function is called in Javascript the value of this inside it is set, so unlike other variables this is always shadowed. If you pass in a second argument you are telling filter that you want this inside your callback to be whatever you passed in. In your case you passed in this from outside the callback, so even though the callback still has it's own this shadowing the outer this, it refers to the same object.

bflydesign Over a year ago

what do I need to change in my fiddle to let it automaticaly update the count when using the searchfield?

Paul Over a year ago

@BFlyDesign I'd never heard of Vue until now, so I'm not sure if this is the best way, but it seems like you just need to call tokens.countFiltered from your filter. See the update here: jsfiddle.net/ukgs5dy7/9

bflydesign Over a year ago

not completely working as intended but you've put me on the right track! Thx

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