Simple question, but it doesn't seem to be working how I expect...
I'm trying to access the value from a nested object, however I'm getting that (for this example) 'person' is not defined.
What am I doing wrong?
Example:
config.settings.js:
var configs = {
person: {
'name': 'John',
'number': 27,
'color': blue
},
place: {
'town': 'springville',
'population': 201827
}
}
module.exports = configs;
main.js:
var configSettings = require('config.settings');
module.exports = {
run: function(){
console.log(configSettings[person][name]);
}
}
You have to use dot accessor such as
configSettings.person.name
And make sure your are properly importing your config.
First make sure blue is defined otherwise is a typo and should be a string
person: {
'name': 'John',
'number': 27,
'color': "blue"
},
and I sugest use dot notation
configSettings.person.name
Had to make the inner keys strings and reference with configSettings.person['name']
Also I had to make the inner keys into strings- e.g. "person:", "place":
I'm just reporting what fixed it for me- I do not understand what the original problem was as of yet, without making the inner keys into strings I was getting type errors when trying to access.
Related
I am have an object that looks like this in the console,
res.local.details > Object {role-details : {} }
so to access this I would need to do res.local.details['role-details']
Is is possible to make it so I can "explode" role-details into details so I can just do
res.locals.details
to access the attributes from role-details
Yes, objects in JS are mutable. If you want to reassign data from one part of your object to another, you can just do it like this:
const myObj = {
name: {
first: 'John',
last: 'Smith',
},
address: {
streetNo: '123',
streetName: 'Main St',
city: {
name: 'Exampletown'
}
}
}
myObj.address.city.name // resolves to Exampletown
myObj.address.city = myObj.address.city.name
myObj.address.city /// resolves to Exampletown
This can be done in several ways.
In this particular case, where details just has that one property, you can just do:
res.local.details = res.local.details['role-details'];
In a more generic situation, details might have other properties that you don't want to destroy with this operation. In that case you can use:
Object.assign(res.local.details, res.local.details['role-details']);
With this, res.local.details will keep all its properties (provided they don't have the same name as properties of role-details), including role-details (but which becomes kind of obsolete).
The same can be achieved with:
res.local.details = {...res.local.details, ...res.local.details['role-details']};
I am struggling to create dynamic nested keys in javascript. My problem is that I need to have a object like this
{
"grandGrandFather": 'A',
"firstGrandFather": {
name: "AA",
children: {
first: 'AAA',
children: {
first: "AAAA"
}
}
},
"secondGrandFather": {
name: "AB",
first: 'ABA',
children: {
first: "ABAA",
second: "ABAB"
}
}
},
"thirdGrandFather": {
name: "AC",
children: {
name: "ACA"
}
}
}
Here problem is that I need to fetch these data from somewhere and I need to create these values dynamically. The prop creation begins from the first level and goes upto fourth level. So my question is how can I create dynamic keys in JS. Also I know you can create dynamic keys in JS like this:
var obj = {
prop1: "a",
prop2: "b",
prop3:'c'
}
obj['prop4'] = 'd';
Also I have been successful in creating a props to a level but when I need to stack these I get confused any help would be appreciated.
Further details about above object
In the above object I created I am getting data from database and I need to add firstGrandFather, secondGrandFather, thirdGrandFather dynamically. Also I don't know what their children props I need to define would be in the object. Some may have spouse,age,work props inside some may not also I don't know how many of these I would get. And these goes on for one or two more level.
In php it would be easy to create these in associative array easily but I am having hard time doing it in JS.
dynamic keys are possible in ES6+ Docs here
Basically, the syntax is:
obj[variable] = value;
Variable must contain a primitive value.
As for stacking, I'm afraid you have to get used to working with deep keys access with either dot or bracket notation. You can also assign a property of your object to a variable and then access its props.
So if obj is the object from your example:
const firstGrandfathersChildren = obj.firstGrandFather.children
It will have the following assigned:
{
first: 'AAA',
children: {
first: "AAAA"
}
}
I have an object :
{
...,
values: {},
...
}
values is empty by default.
Now I want to add dynamic object to this object :
[myDynamicProperty]: {
title: '...',
introduction: '...'
}
That's ok, I know how to do this. But, on other action, I have to add key: value or key: object to [myDynamicProperty], when I try something, I loose the values of my [myDynamicProperty]
I've tried to clone my initial object, but it doesn't work.
For sure, someone on stackoverflow has the solution.
You could take a two step approach by assigning a default object to myDynamicProperty and then assign the values to it.
This keeps all properties of object.values[myDynamicProperty] and changes only the given keys.
var object = {
values: {},
}
object.values[myDynamicProperty] = object.values[myDynamicProperty] || {};
Object.assign(object.values[myDynamicProperty], { title: '...', introduction: '...' });
If you are trying to convey that you are starting with an object such as:
var user = {
meta: {
first_name: "John",
last_name: "Smith"
}
}
and wish to add middle_name to the meta object property, then you should do the following.
Object.assign(user['meta'], {middle_name: "Harry"});
Note that the first object will be overwritten with values from the later object(s). The later object properties will take precedence over previous objects properties. See Mozilla for further details. WARNING: This is an ES6 feature, use a polyfill for backwards compatibility if necessary.
I am using Dexie IndexedDB wrapper and I am trying to add an object to an existing array which in inside a nested object. The structure looks similar to below
{
Name : 'John',
age : 33,
tags : {
skill: [{
first: '.NET',
second: 'JAVA',
third: [{special1:'sleep'},{special2:'eat'}]
}]
}
}
I have tried many way to push object special3:'run' to skill.third but without success. My last attempt looked something like this
const pathObject = {};
const fullPath = 'result.tags.skill[3].third';
pathObject[fullPath] = {special3:'run'};
db.inspections.update(id, pathObject);
The object is added outside and not inside the array 'third' something like below
{
Name : 'John',
age : 33,
tags : {
skill: [{
first: '.NET',
second: 'JAVA',
third: [{special1:'sleep'},{special2:'eat'}]
}]
skill[3]: {
third: {special3:'run'}
}
}
}
I wish to know if there a way to add to arrays in nested object using Dexie if not is there a way to achieve this using indexeddb. Help is appreciated as problem is been holding back progress
The easiest is to use Collection.modify() with a callback function to mutate your model:
db.inspections.where('id').equals(id).modify(x =>
x.tags.skill[0].third.push({special3:'run'}) );
If you want to use a keypath containing array items, it is also possible, as arrays can be looked at as objects with numeric keys:
db.inspections.update(id, {"tags.skill.0.third.3": {special3:'run'}});
So I have the following object structure:
const SamplePalette = {
id: 1,
name: "Sample Palette",
description: "this is a short description",
swatches: [
{
val: "#FF6245",
tints: ["#FFE0DB", "#FFA797"],
shades: ["#751408", "#C33F27"]
},
{
val: "#FFFDA4",
tints: ["#FFFFE1"],
shades: ["#CCCB83"]
},
{
val: "#BFE8A3",
tints: ["#E7FFD7"],
shades: ["#95B77E"]
}
]
}
Let's imagine that this object is managed by the state of my app like this:
this.state = {
currentPalette: SamplePalette,
}
My question is how would I go about updating the val property of a given swatch object in the swatches array? Or more generally - how do I only update pieces of this object?
I tried using the update helper as well as to figure out how Object.assign() works, however I've been unsuccessful and frankly can't really grasp the syntax by just looking at examples.
Also, since I'm going to be modifying this object quite a lot, should I look into maybe using Redux?
[EDIT]
I tried #maxim.sh suggestion but with no success:
this.setState(
{ currentPalette: {...this.state.currentPalette,
swatches[0].val: newValue}
})
Consider you have new new_swatches
I think the clearer way is to get array, update it and put back as:
let new_swatches = this.state.currentPalette.swatches;
new_swatches[0].val = newValue;
this.setState(
{ currentPalette:
{ ...this.state.currentPalette, swatches: new_swatches }
});
Also you have : Immutability Helpers or https://github.com/kolodny/immutability-helper
Available Commands
{$push: array} push() all the items in array on the target.
{$unshift: array} unshift() all the items in array on the target.
{$splice: array of arrays} for each item in arrays call splice() on the target with the parameters provided by the item.
{$set: any} replace the target entirely.
{$merge: object} merge the keys of object with the target.
{$apply: function} passes in the current value to the function and updates it with the new returned value.