What is the recommended way to check if an object property like obj.prop.otherprop.another is defined?
if(obj && obj.prop && obj.prop.otherprop && obj.prop.otherprop.another) this works well, but enough ugly.
- stackoverflow.com/questions/135448/…JonH– JonH2013-02-15 17:52:48 +00:00Commented Feb 15, 2013 at 17:52
- @JonH no, not really...Matt Ball– Matt Ball2013-02-15 17:53:58 +00:00Commented Feb 15, 2013 at 17:53
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3 Answers
The most efficient way to do it is by checking for obj.prop.otherprop.another in a try{} catch(exception){} block. That would be the fastest if all the remaining exist; else the exception would be handled.
var a = null; try { a = obj.prop.otherprop.another; } catch(e) { obj = obj || {}; obj.prop = obj.prop || {}; obj.prop.otherprop = obj.prop.otherprop || {}; obj.prop.otherprop.another = {}; a = obj.prop.otherprop.another ; } 1 Comment
jagzviruz
Please don't use this.. this is just stupid of me to suggest this.
Not saying this is better but ...
x = null try { x = obj.prop.otherprop.another; } catch() {} // ... Or alternatively ...
function resolve(obj, path) { path = path.split('.'); while (path.length && obj) obj = obj[path.shift()]; return obj; } x = resolve(obj, 'prop.otherprop.another'); ... but I guess the actual answer is that there isn't a best-practice for this. Not that I'm aware of.
Comments
If you're in a silly mood, this would work:
if ((((obj || {}).prop || {}).anotherprop || {}).another) { ... } But I don't know if initializing three new objects is really worth not having to repeatedly type out the path.
