is it possible to get a reference to an object with the object itself
obj
and the attributes in string form
'address.town.street'
so that at the end it resolves
obj.address.town.street
i could immageine smth like the eval() function.
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1noooo. Do not use eval!scrblnrd3– scrblnrd32014-01-22 16:22:17 +00:00Commented Jan 22, 2014 at 16:22
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any quick explanation why not to use it besides it is very slow?alknows– alknows2014-01-22 16:36:36 +00:00Commented Jan 22, 2014 at 16:36
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In general bad practice, teaches bad habits when there are good alternatives (like this one)scrblnrd3– scrblnrd32014-01-22 16:37:42 +00:00Commented Jan 22, 2014 at 16:37
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2 Answers
Try
function getValue(obj, path) {
return path.split(".").reduce(function(obj, name){ return obj[name]}, obj);
}
4 Comments
Scott Sauyet
Just remember that if any of your intermediate objects, say
town is null or undefined, this will throw an exception. If you have to add null-checking it gets significantly more complicated.
Yury Tarabanko
@ScottSauyet 'more complicated'? Simple
return obj&&obj[name] will almost do the trick. It will return false if path element was falsy.Scott Sauyet
@YuryTarabanko: You're absoultely right. It's not much more complicated. It won't necessarily return false, but that false-y value, but that's probably better anyway. This is so much simpler than approaches I've done (granted the problems were more complicated), but I thought the same null-checking issues would definitely rear their ugly heads here. Nicely done!
jacqbus
This is one-liner which allows You to go one step further - it returns particular falsy value (in this case
null): path.split(".").reduce((obj, key) => obj && obj[key] || null, obj);Do not use eval. Use this instead
Object.prototype.nestedByString=function(reference){
var current=this;
path=reference.split(".");
for(var i=0;i<path.length;i++){
current=current[path[i]];
}
return current;
}
Here is a demo
I suppose that if you're allergic to extending native prototypes, you can do this
function nestedByString(obj,reference){
var current=obj;
path=reference.split(".");
for(var i=0;i<path.length;i++){
current=current[path[i]];
}
return current;
}
10 Comments
Yury Tarabanko
Bad idea to spoil
Object.prototype.
scrblnrd3
Why is it a bad idea? It was built into the language for a reason
Yury Tarabanko
Well, cos another developers don't give a heck what this method is for. And this code will potencially break
for-in loops without .hasOwnProperty checking.scrblnrd3
this doesn't use a for in loop
Yury Tarabanko
You can fix it in modern browsers by defining non-enumerable property.
Object.defineProperty(Object.prototype, 'nestedByString', {value: function(){/*blah*/}, enumerable: false}) |