string objects comparison always returning false

Question

Here is the code that I am executing:

filterIssues: function(objectKey, text){
    var view = this;
    var keys = objectKey.split(".");
    var attributeKey = keys[0];
    var attributeName;
    if (keys.length > 1){
        attributeName = keys[1];
    }
    view.issues.each(function(issue){
        var value = issue.get(attributeKey);
        console.log(text);

        if (value === undefined || value === null){
            issue.trigger("hide");
            return;
        }

        if (attributeName !== undefined){
            value = value[attributeName];
        }

        if(value !== undefined){
            var matchedText = value.substring(0, text.length - 1);
            if ( matchedText === text){
                issue.trigger("show");
                console.log(value);  
                return;     
            }
        }
        issue.trigger("hide");
    });
}

The matchedText == text always returns false.

This is what I get when I play around with the console:

> matchedText
"sande"
> text
"sande"
> typeof(text)
"string"
> typeof(matchedText)
"string"
> matchedText === text
false
> matchedText == text
false

I do realize that and === will always check if both the objects are the same and I have read JavaScript equal operations anomalies and Javascript string equality.

Is there something wrong in the code that I am overlooking?

What sort of object is `issues` and what does `issues.each()` pass to the function (i.e. what is `issue`)? What does `issue.get()` return? — RobG, Nov 22 '13 at 05:31
Maybe fence post error? `var matchedText = value.substring(0, text.length - 1);` did you try without - 1? what does `matchedText.valueOf() === text.valueOf()` or with (==) give you? — James, Nov 22 '13 at 05:32
@James `matchedText.toString() == text.toString()` returns `false` and so does `===` — satran, Nov 22 '13 at 05:44
@FelixKling aaah... the length is different. I changed `text.length - 1` to `text.length` and still the same. — satran, Nov 22 '13 at 05:47
@Satyajit hmm just to be sure you could try `+ 1` (to rule out fence-post-error lol) but perhaps it's some crazy javascript quirk? What does `issue.trigger("hide")` do? — James, Nov 22 '13 at 05:58
@James it triggers an event which will be caught by the backbone model. I have commented out the code and yet it has the same problem. It is just bonkers. — satran, Nov 22 '13 at 06:25

bitfiddler · Answer 1 · 2013-11-22T05:44:10.450

0

I think you are misusing the subString() method. If you use subString(), use the length without -1.

edited Nov 22 '13 at 05:44

answered Nov 22 '13 at 05:38

bitfiddler

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I changed the length without -1 and still the same. – satran Nov 22 '13 at 05:47
Using length-1 is definitely wrong. The substring must be the same length as the text for the caparison to be true, not 1 less. – bitfiddler Nov 22 '13 at 05:58
Well I changed the code to use slice instead of substring. Still the same problem. – satran Nov 22 '13 at 06:25

score 0 · Accepted Answer · answered Nov 23 '13 at 13:03

Well I eventually found out what was the problem. Thanks for your responses and I believe you might not have come across the answer for the lack of information.

The problem lied in the text value that I was passing to the function. The text contained a "" at the end and that's why comparison just did not work.

string objects comparison always returning false

2 Answers2