I have an object like: const obj = { 'abc': {'def': 1 } } and I have an array like const arr = ['abc', 'def'] How can I access obj.abc.def property of my object with the array?
Obviously, obj[arr] doesn't work, also obj[arr.join('.') doesn't work.
What I want to do is:
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
const value = obj[arr] // crash
// value should contain 1
You could take a dynamic approach and reduce the keys and take a default object, if a part is not accessable.
const
getValue = (object, keys) => keys.reduce((o, k) => (o || {})[k], object),
obj = { abc: { def: 1 } },
arr = ['abc', 'def'],
value = getValue(obj, arr);
console.log(value);
console.log(getValue(obj, ['foo', 'bar']));The base is
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
console.log(obj[arr[0]][arr[1]]);or if you need to do it with a function...
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
function access(obj, arr) {
return arr.reduce((o, key) => o[key], obj);
}
console.log(access(obj, arr));
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
var value = obj;
for(let key of arr){
value = value[key];
}
console.log(value);You can access the array property by index only. so arr[0] will work.
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
const value = obj[arr[0]][arr[1]]
console.log(value)or you can run the loop over it.
const obj = { 'abc': {'def' : {'ghi': 1 } } };
const arr = ['abc', 'def', 'ghi'];
let ans = null;
for (let i=0; i<arr.length; i++) {
if(i==0) {
ans = obj[arr[0]];
}
else {
ans = ans[arr[i]];
}
}
console.log(ans)
arr.lengthYou can use Array#reduce for a dynamic array.
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def']
const res = arr.reduce((o,prop)=>o[prop], obj);
console.log(res);If you do not want errors to be thrown on properties that do not exist, you can use the optional chaining operator.
const obj = { 'abc': {'def': 1 } }
const arr = ['abc', 'def', 'notdefined', 'notdefined2']
const res = arr.reduce((o,prop)=>o?.[prop], obj);
console.log(res);What you try to do is somewhat called object value "get by path", some library have support this and for example ramda is a production-ready library for that, you should not try to reinvent the wheel (practice is okay)
In your context, ramda's path method could help you achieve to the case of arbitrary array of properties
const obj = {
'abc': {
'def': 1,
'ghi': {
'jkl': 10
}
}
}
console.log(R.path(['abc', 'def'], obj))
console.log(R.path(['abc', 'ghi'], obj))
console.log(R.path(['abc', 'ghi', 'jkl'], obj))
console.log(R.path(['abc', 'ghi', 'jkl', 'mno'], obj))<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>
