I have this object:
var object = {item : {id : "51524512541"}};
Some service is passing this string:
var str = "item.id";
And I want to extract the id (51524512541).
Splitting by . (dot) is an option, but the object may be very deep.
Can maybe eval with try catch can help here somehow?
You can use reduce for this - go through array of indices and dive deeper into the object:
str.split('.').reduce((a, i) => a[i], object)
Explanation:
First, str is split into array, forming:
['item', 'id'].reduce((a, i) => a[i], object)
So You have array of indices, that You want to "visit". Now You call reduce on it - it takes the indices one by one and calls a function on every one of them (the i) and result of previous call (the a) and returns a[i], so it "dives" one level deeper in the object. The first call has no "previous result" available yet, so it takes the object as initial value.
So the real calls look like this:
i = 'item', a = {"item":{"id":123}} -> result a[i] is {"id":123}
i = 'id', a = {"id":123} -> result a[i] is 123
res contains the result value (not object[res]).You could break the string up using split:
var splitStr = str.split('.')
Then use reduce to dive into the object.
const reducer = (accumulator, index) => accumulator ? accumulator[index] : accumulator
splitStr.reduce(reducer, object)
This should give you the result.
Check out more on reducers here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce
Alternative option, which is probably more efficient:
let result = object
for(let str of splitStr) {
if(!result) break;
result = result[str]
}
Here's a JS Fiddle:
reduce would be more appropriate here since you convert array to something else
x.y and an empty object {}. ;)(accumulator, index) => accumulator ? accumulator[index] : accumulator to fix this?for...of. You can break from a loop early.
_.getlodash.com/docs/4.17.10#getgetor one of the solutions offered here.