Check if function exists in array

Question

I have a kinecticjs image object I am applying filters to based on some parameters, however when it needs to be redrawn it will apply the filter again, meaning it will duplicate the filter.

I know i should be doing some sort of check but its applies a function right to an array.

//create object
var image = new Kinetic.Image({
    image: alreadyLoadedImageObject
});

function addFilter(shouldAdd){
    if(shouldAdd){
        var filters = image.filters() || [];

        filters.push(Kinetic.Filters.RGB);

        image.filters(filters);
    }
}

layer.add(image);
stage.add(layer);

addFilter(true);
stage.draw();

setTimeout(function(){
    addFilter(true);
    stage.draw();
},500);

That should roughly show what i am currently doing, in this case once the time out runs there will be 2 Kinetic.Filters.RGB applied to the image object.

I consider this a general javascript question rather then just kineticjs, as the root is that I need to somehow know that there already is a Kinetic.Filters.RGB function within the filters array.

So 2 questions, is there anyway to check with something like Array.indexOf that a function name already exists in the array? or is there already some sort of prebuilt method in KineticJS for this I have not seen?

sabithpocker · Accepted Answer · 2015-01-25 00:55:41Z

5

x = function(){};
y = function(){};
a = [];
a.push(x);
a.indexOf(x); //0
a.indexOf(y); //-1

So you can try:

if(filters.indexOf(Kinetic.Filters.RGB) !== -1)

answered Jan 25, 2015 at 0:55

sabithpocker

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1 Comment

user2924536 Over a year ago

Never thought this would work, everything i seen said indexOf was string only. I ended up going with another solution that fit my project but this is good to know, tested it with a jsfiddle here jsfiddle.net/q3umxbcz

Raunaq Sachdev · Accepted Answer · 2016-10-14 03:56:18Z

0

You can also check using the some() function.

if(!filters.some((val) => {val == Kinetic.Filters.RGB}))

answered Oct 14, 2016 at 3:56

Raunaq Sachdev

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