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Function with Multiple Returns

Participant ,
Jan 28, 2020 Jan 28, 2020

I have this little script for getting objects on a given page:

function getFieldOn(name, p){//finds (the first) field on page p with 'name' in its name
    var fields;
    for(var i = 0; i < this.numFields; i++){
        var f = this.getField(this.getNthFieldName(i));
        if ((f.name.indexOf(name) > -1) && (f.page == p)) return f;
    }
}

I'd like to modify this so it can return a single object if that's all it finds, and return an array of objects if there are multiple objects sharing the same name or partial name. Can I have two types of return values like that? How can I modify this code?

TOPICS
Acrobat SDK and JavaScript
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correct answers 1 Correct answer

Community Expert , Jan 28, 2020 Jan 28, 2020

Add an array object to collect all the fields. 

 

    var fieldsd, aRslts = [];
    for(var i = 0; i < this.numFields; i++){
        var f = this.getField(this.getNthFieldName(i));
        if ((f.name.indexOf(name) > -1) && (f.page == p)) aRslt.push(f);
    }
    return (aRslts.length==1)?aRslts[0]:aRslts;

 

Note that this code returns an empty array if there are no fields found.  

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Community Expert ,
Jan 28, 2020 Jan 28, 2020

You can return a single object or an array of objects.

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Community Expert ,
Jan 28, 2020 Jan 28, 2020

Add an array object to collect all the fields. 

 

    var fieldsd, aRslts = [];
    for(var i = 0; i < this.numFields; i++){
        var f = this.getField(this.getNthFieldName(i));
        if ((f.name.indexOf(name) > -1) && (f.page == p)) aRslt.push(f);
    }
    return (aRslts.length==1)?aRslts[0]:aRslts;

 

Note that this code returns an empty array if there are no fields found.  

Thom Parker - Software Developer at PDFScripting
Use the Acrobat JavaScript Reference early and often

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Participant ,
Jan 28, 2020 Jan 28, 2020

Sweet, thanks! Why is the logic check needed in the last line of your code?

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Community Expert ,
Jan 28, 2020 Jan 28, 2020

The conditional on the return tests for a single result. If there is only one, then it returns just that one. Otherwise the entire array is returned. 

Thom Parker - Software Developer at PDFScripting
Use the Acrobat JavaScript Reference early and often

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Participant ,
Jan 28, 2020 Jan 28, 2020

I'm sure this is "best programming practice" at work, but I want to make sure I understand. Why do we need to check for this? What if the last line wre just

return aRslts;

and there was only one value in the array? 

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Community Expert ,
Jan 28, 2020 Jan 28, 2020

Then it would only return that one object, not an array.

Personally, I think it's better to know the type of object you're returning, so I would opt for returning an array always, either empty, or with one item, or with multiple items, but it's a matter of preference.

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Community Expert ,
Jan 28, 2020 Jan 28, 2020
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Personally I think you are better off just returning the "aRslts" array as you've just suggested. I presented the code as you asked for it. You specifically asked for two types of return objects. 

Thom Parker - Software Developer at PDFScripting
Use the Acrobat JavaScript Reference early and often

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