Because I'm dealing with a relatively big object, I want to be able to modify my object value dynamically by defining a "path".
let a="x", b="y", c="z"
let objKeys = [a, b, c]
let value = 5
obj = {x:
{y:
{z: 1
}
}
}
I want to be able to achieve this.
obj[a][b][c] = value;
Is there any way to do this? I tried obj(eval(`["a"]["b"]["c"]`)) = value but it says that "invalid left-hand side in assignment".
You can achieve this by using the array reduce function:
const objProps = ["a","b","c"]
const value = 5
const newObj = objProps.reverse().reduce((result, curProp)=> (
{
[curProp]: result
}
), value)
console.log(newObj)
This will "chain" the prop inside of each other, starting with the last value in objProps. Because you want to use names as indices use an object instead of array.
EDIT: ok, so I read your question again and as I understood you don't want to create a new object but modify values inside of a big object by defining a path. For this have a look at lodash. This library has a method set where you can provide a path to the location of the property and set a new value (https://lodash.com/docs/4.17.11#set).
By using an array of keys and an object, you could reduce this object by accessing the object with each key and return the final object. Then take the last key and assign the value.
This approach add a new object as a default value for not given properties.
function setValue(object, keys, value) {
var target = keys.pop();
keys.reduce((o, k) => o[k] = o[k] || {}, object)[target] = value;
}
var obj = { x: { y: { z: 1 } } };
setValue(obj, ['x', 'y', 'z'], 5);
console.log(obj);
let obj = {
a: {
b: {
c: 'hey',
}
}
}
let objProps = ["a", "b", "c"];
function findValue(obj, objProps, index = 0) {
if (index > objProps.length-1) return obj;
return findValue(obj[objProps[index]],objProps, index+1)
}
findValue(obj, objProps)
let obj = {
a: {
b: {
c: 'hey',
}
}
}
let objProps = ["a", "b", "c"];
function assignValue(obj, objProps, newValue, index = 0) {
console.log(obj)
if (index >= objProps.length-1 && obj[objProps[index]]) {
return obj[objProps[index]] = newValue;
} else {
return assignValue(obj[objProps[index]],objProps, newValue, index+1)
}
}
assignValue(obj, objProps, "asdsa")
A quick solution i crafted, i'm sure you can make it work with eval, if you show us the actual value's i can try and post a solution with that
However for this hack:
let objProps = ['a', 'b', 'c'];
let value = ?;
let tmp;
let result = objProps.reduce((acc, curr) => {
let tmp_v2 = acc;
while (Object.keys(tmp).length > 0) {
tmp_v2 = tmp[Object.keys(tmp_v2)[0]]
}
tmp_v2[curr] = {};
tmp = tmp_v2;
return acc
}, {})
tmp.c = value;
now result would look like:
{
"a": {
"b": {
"c": value
}
}
}
as wanted.
{key:value}. What you have shown in that example is a list represented as an Array. That is part of the reason your question is unclear. Please try to edit your question so we can understand your intent.