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Function parameter value isn't working in object-destructuring in JS

Let's assume that I've the following object:
let filters = {
brands: { ... },
price: { ... },
sizes: { ... },
...
}
The properties of the filters object will be set by the users. Which means sometimes the filters object may contain just brands, sometimes it may contain brands & price and so on.
I've written the following function to extract a specific property from the filters object:
let extractProperty = (propertyName) => {
({ propertyName, ...rest } = filters); // <-- propertyName isn't working here
console.log(propertyName);
}
extractProperty("brands");
If I invoke the above function, the console displays undefined.
Can anyone please point me out what I'm missing here?
CodePen Link
Note:
I've already resolved this issue using lodash.omit method. But I'm still curious to know why function parameter value isn't working in object-destructuring.
Not Duplicate:
This question is about passing default value

That code is looking for a property called propertyName, literally. To use the value in propertyName as the property name, you need to use computed notation, and you'll need to specify where to put the property's value. For instance, to put it in an existing example variable:
let extractProperty = (propertyName) => {
({ [propertyName]: example, ...rest } = filters);
// ^−−−−−−−−−−−−^^^^^^^^^^
console.log(example);
};
extractProperty("brands");
Your code is written assuming that rest already exists, but I suspect you really want to declare it locally, along with the variable to receive the property value:
let extractProperty = (propertyName) => {
const { [propertyName]: example, ...rest } = filters;
console.log(example);
};
extractProperty("brands");
Without const, let (or var, but var is deprecated), unless you have rest declared in an enclosing scope, that code will either fail with a ReferenceError (in strict mode) or fall prey to what I call The Horror of Implicit Globals (in loose mode), automatically creating a global variable.

why use destructuring here when you just want to get a property?
let filters = {
brands: { value:'b' },
price: { value:'p' },
sizes: { value:'s' },
}
let extractProperty = propertyName =>
console.log(filters[propertyName])
extractProperty("brands");

How to pass by value and not by reference in React?

I have the following file, LookupPage.jsx and AccountDetails.jsx.
In LookUp
this.updateCustomer = (customer) => {
if(JSON.stringify(customer.address) !== JSON.stringify(this.state.activeAccount.customer.address)) {
console.log('address changed');
customer.update_address = true;
customer.address.source = 'user';
}
return fetch(
`${API_ENDPOINT}/customer/${customer.id}/`,
{
method: 'PATCH',
headers: {
'Authorization': 'Token ' + this.props.session_token,
'Content-Type': 'application/json',
},
body: JSON.stringify(customer),
}
).then(restJSONResponseToPromise).then(responseJSON => {
if(responseJSON.results){
console.log('update customers client side.')
}
}, clearSessionIfInvalidToken(this.props.clearSession));
};
<AccountsDetailModal
show={this.state.showAccountDetail}
close={this.toggleAccountDetail}
customer={this.state.activeAccount.customer}
updateCustomer={this.updateCustomer}
/>
In side AccountDetails
this.onChangeAddress = (e) => {
const customer = {...this.state.customer};
const address = customer.address;
address[e.target.name] = e.target.value;
customer.address = address;
this.setState({customer, errors: {
...this.state.errors,
[e.target.name]: [],
}});
};
this.saveCustomer = () => {
this.setState({postDisable: true});
const errors = this.getFormErrors();
const hasErrors = !every(errors, (item) => !item.length);
if(!hasErrors){
this.props.updateCustomer(this.state.customer);
} else {
sweetAlert('Error!', 'Form is invalid.', 'error');
}
this.setState({postDisable: false});
};
this.componentDidMount = () => {
this.setState({customer: this.props.customer});
}
When I am updating the customers address, it is updating active accounts address, so it seems like it is being passed by reference. What I want to happen is only update the customer address if the address was changed/different from the original. How would I modify my code to do this?

You can pass any object by value in JS (whether you're using React or not) by passing:
JSON.parse(JSON.stringify(myObject))
as an argument instead of the object itself.
Essentially this will just clone the object and pass a copy of it, so you can manipulate the copy all you want without affecting the original.
Note that this will not work if the object contains functions, it will only copy the properties. (In your example this should be fine.)

I am going to put my two cents here:
First of all, this isn't really specific to React and is more of a JS related question.
Secondly, setting props against internal state is considered to be a bad practice when it comes to react. There's really no need to do that given your particular scenario. I am referring to
this.setState({customer: this.props.customer});
So, coming to your problem, the reason you are having reference issues is because you are mutating the original passed in object at certain points in your code. For instance, if I look at:
this.updateCustomer = (customer) => {
if(JSON.stringify(customer.address) !== JSON.stringify(this.state.activeAccount.customer.address)) {
console.log('address changed');
customer.update_address = true;
customer.address.source = 'user';
}
};
You are mutating the original props of the argument object which is very likely to be passed around in other methods of your component. So, to overcome that you can do:
const updatedCustomer = Object.assign({}, customer, {
update_address: true
});
And you can pass in updatedCustomer in your API call. Object.assign() will not perform operation on the passed in object but will return a new object so you can be sure that at any point in your app you are not mutating the original object.
Note: Object.assign would work on plain object and not a nested one. So, if you want to achieve something similar that would work on nested object properties too, you can use lodash merge.

inside Array.push without a function call

I want to perform more logic before writing an element to an array:
tempDatensatz.push( () => {
var current = window.dataForDataTable[i].outbounds[key].updatedAt;
if (current) {
return current.toString();
} else {
return "".toString();
}
});
Getting the value from that array will be achieved like this:
tempDatensatz[0]()
But I want the same logic in it without having a function to call. I need a normal array, where I get a value like this:
tempDatensatz[0]
What can I do instead?
Updated
I published my project to gitHub, you can take a look if you need a better understanding :)
https://github.com/te2020/GoEuro/blob/master/GoEuro/Views/Home/Index.cshtml

Use an immediately invoked function instead of just a function:
tempDatensatz.push( (function(){
var current = window.dataForDataTable[i].outbounds[key].updatedAt;
if (current) {
return current.toString();
} else {
return "".toString();
}
})());
The function will be executed immediatly after it definition, returning the result. So push won't push a reference to that function but instead it will push it returned value (the result).

You can write a proxy as follows:
function makeProxy(array) {
return new Proxy(array, {
get(target, property) {
return !isNaN(property) ? target[property]() : target[property];
}
});
}
const tempDatensatz = [];
const useThisOne = makeProxy(tempDatensatz);
useThisOne.push(() => alert("Hi, Jane!"));
useThisOne[0];
Pushing/writing to the array will work as expected, but retrieving its elements will go through the get handler, which will execute the function.

You could just use an expression, like:
tempDatensatz.push(
(window.dataForDataTable[i].outbounds[key].updatedAt || '').toString();
);
For more complex expressions you can often use the ternary operator. For the above that would look like this:
tempDatensatz.push(
window.dataForDataTable[i].outbounds[key].updatedAt
? window.dataForDataTable[i].outbounds[key].updatedAt.toString()
: ''
);
Your code
When looking at the github code you linked to, you can do all that pushing with this "oneliner":
var tempDatensatz =
['companyId', 'mode', 'duration', 'outboundId', 'journeyId', 'departureTime',
'arrivalTime', 'stops', 'price', 'updatedAt', 'segments']
.map( prop => (window.dataForDataTable[i].outbounds[key][prop] || '').toString() );

Loop in js for specific value without if

I use the following code which is working great but I wonder if in JS there is a way to avoid the if and to do it inside the loop, I want to use also lodash if it helps
for (provider in config.providers[0]) {
if (provider === "save") {
....

You can chain calls together using _.chain, filter by a value, and then use each to call a function for each filtered result. However, you have to add a final .value() call at the end for it to evaluate the expression you just built.
I'd argue that for short, simple conditional blocks, an if statement is easier and more readable. I'd use lodash- and more specifically chaining- if you are combining multiple operations or performing sophisticated filtering, sorting, etc. over an object or collection.
var providers = ['hello', 'world', 'save'];
_.chain(providers)
.filter(function(provider) {
return provider === 'save';
}).each(function(p) {
document.write(p); // your code here
}).value();
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.8.0/lodash.js"></script>
Edit: My mistake; filter does not have an overload where you can just supply a literal value. If you want to do literal value checking you have to supply a function as in my amended answer above.

I'd argue that what you have there is pretty good, clean and readable, but since you mentioned lodash, I will give it a try.
_.each(_.filter(config.providers[0], p => p === 'save'), p => {
// Do something with p
...
});
Note that the arrow function/lambda of ECMAScript 6 doesn't come to Chrome until version 45.

Basically, you are testing to see if config.providers[0], which is an object, contains a property called save (or some other dynamic value, I'm using a variable called provider to store that value in my example code below).
You can use this instead of using a for .. in .. loop:
var provider = 'save';
if (config.providers[0][provider] !== undefined) {
...
}
Or using #initialxy's (better!) suggestion:
if (provider in config.providers[0]) {
...
}

How about:
for (provider in config.providers[0].filter(function(a) {return a === "save"}) {
...
}

Strategy, you are looking for some kind of strategy pattern as,
Currenlty the save is hardcoded but what will you do if its coming from other varible – Al Bundy
var actions = {
save: function() {
alert('saved with args: ' + JSON.stringify(arguments))
},
delete: function() {
alert('deleted')
},
default: function() {
alert('action not supported')
}
}
var config = {
providers: [{
'save': function() {
return {
action: 'save',
args: 'some arguments'
}
},
notSupported: function() {}
}]
}
for (provider in config.providers[0]) {
(actions[provider] || actions['default'])(config.providers[0][provider]())
}
Push „Run code snippet” button will shows two pop-ups - be carefull

It is not clearly stated by the original poster whether the desired output
should be a single save - or an array containing all occurrences of
save.
This answer shows a solution to the latter case.
const providers = ['save', 'hello', 'world', 'save'];
const saves = [];
_.forEach(_.filter(providers, elem => { return elem==='save' }),
provider => { saves.push(provider); });
console.log(saves);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.19/lodash.js"></script>

Javascript: Defining a map of functions

$("#searchType").on('change', function () {
var selectionAction = {
All: loadAll(),
Competitions: loadAll("competitions"),
Clubs: loadAll("clubs"),
Teams: loadAll("teams")
};
var selection = $("#searchType").find('option:selected').val();
selectionAction[selection]
});
See the above code. The idea is that when selection equals one of the properties in my object, then the corresponding function will be called.
e.g. when selection equals Competitions then we would invoke loadAll("competitions") function.
Instead what I am finding is that when it enters the onChange function that it invokes all functions.
What am I doing wrong here?

Use anonymous functions to make the call. Currently you are storing the result of the function call which is undefined
var selectionAction = {
All: function(){loadAll()},
Competitions: function(){loadAll("competitions")},
Clubs: function(){loadAll("clubs")},
Teams: function(){loadAll("teams")}
};
var selection = $("#searchType").find('option:selected').val();
selectionAction[selection]();// make sure to call the anonymous function
Or, if you prefer brevity,
$("#searchType").on('change', function () {
loadAll($("#searchType").find('option:selected').val().replace("All","").toLowerCase())
});

When you specify loadAll(), loadAll("competitions"), loadAll("clubs") and so on you are actually executing the function immediately. What you want to do is have your object have properties of non-function calls like so:
var selectionAction = {
All: '',
Competitions: 'competitions',
Clubs: 'clubs',
Teams: 'teams'
};
And then do:
var selection = $("#searchType").find('option:selected').val();
loadAll(selectionAction[selection]);
And make sure your loadAll function checks for existence of its 1st argument.