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POConcise way to accept an options object as an argument, falling back to defaults for omitted properties
 

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  1. POConcise way to accept an options object as an argument, falling back to defaults for omitted properties
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    <p>I have a function which may be called with an optional object containing multiple options, each of which should fall back to a default value if omitted.</p> <p>I'm currently doing this like so:</p> <pre><code>function f(options){ var _options = options || {}; _options.propertyOne = options.propertyOne || 50; _options.propertyTwo = options.propertyOne || 100; _options.propertyThree = options.propertyThree || {}; _options.propertyThree.subPropOne = options.propertyThree.subPropOne || 150; //etc... } var options = { propertyOne: 20, propertyThree: { subPropOne: 100 } } f(options); </code></pre> <p>However, as the number of options grows, the code is looking increasingly messy. There's also the potential problem of false/zero values being ignored (though all properties are currently numerical and non-zero).</p> <p>Is there a more effective, more concise way of achieving this? I've considered creating an object initialised to default values within my function, then recursively copying any options supplied in the argument to it, but I'm not sure if doing so could introduce new problems that I haven't thought of yet.</p> <p><strong>Edit:</strong></p> <p>The function I would use to recursively copy properties:</p> <pre><code>function copyOptions(from, to){ for(var i in from){ if(typeof from[i] == "object"){ to[i] = copyOptions(from[i], to[i]); }else if(typeof from[i] != "undefined"){ to[i] = from[i]; } } } </code></pre>
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    1. USJim
    1. USJim
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    1. COUsing an object an copying the properties would be the way to go. Instead of creating it inside the function, you could also create it as property of the function or use an immediate function to create a private scope and define the default options there.
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      1. USFelix Kling
    2. COin plain javascript this could be useful: http://stackoverflow.com/questions/171251/how-can-i-merge-properties-of-two-javascript-objects-dynamically - the idea is to merge two different objects, like it happens on jQuery plugin with `$.merge`
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      1. USfcalderan
    3. COI've edited the question to include the recursive alternative I'm considering, does that look correct?
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      1. USJim
 

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