Question

I want to make set with for my own objects witch can recognize same objects at append and falls them.

function ImageSet(){
    this.set = [];
}

ImageSet.prototype.length = function(){return this.set.length}
ImageSet.prototype.process = function(imgObj){
    var is_exist = false;
    $.each(this.set, function(i){
        if (this.set[i].imgHash == imgObj.imgHash){is_exist = true};
    });

    if (!is_exist){
        this.set[this.set.length + 1] = imgObj;
        return true;
    }
    return undefined;
}

var imagesChoosen = new ImageSet();

And so when user click on element I create new object and try append it to my ImageSet.
On the first click object successfully append to set, but on second click console write error

TypeError: this.set is undefined if (this.set[i].imgHash == imgObj.imgHash){is_exist = true};  

And code which call ImageSet is:

$('#content_table a').click(function(event){
    event.preventDefault();
    el = new Image($(this).attr('href'));
    if (imagesChoosen.process(el)){
        $(this).parent().css("border", "3px dotted orange");    
    } else {
        $(this).parent().css("border", "None");
    }
    console.log(imagesChoosen.length());
    return false;
});

I can’t understand. Is my ImageSet is destruct after the first call?

Answer 1

this.set[this.set.length + 1] = imgObj;

think should be:

this.set[this.set.length] = imgObj;

I am not familiar with the JQuery each function but previous posts would indicate changing of this context so I would change the for each:

$.each(this.set, function(i){
    if (this.set[i].imgHash == imgObj.imgHash){is_exist = true};
});

to:

for(var i=0;i<this.set.length;i++){
    if (this.set[i].imgHash == imgObj.imgHash){is_exist = true};
};