Access a nested property with a string [duplicate]

Access a nested property with a string [duplicate] - javascript

This question already has answers here:
Accessing nested JavaScript objects and arrays by string path
(44 answers)
Closed 4 years ago.
var person = {
name: 'Joe',
contact: {
phone: '555'
}
}
var nameOfPerson = person['name']; //Joe
var str = 'contact.phone';
var phoneToPerson = person[str]; //undefined
Is this possible to do somehow? I got some logic where I end up with a string and I need to access a nested property with it.
https://jsbin.com/xehokozaco/edit?js,console

You'll have to split the string by the period, and then access each node iteratively. This could be done in a simple reduce:
var value = str.split('.').reduce(function(p,prop) { return p[prop] }, person);
The above would work regardless if str contains a period or not, i.e. for name as well as contact.phone.

You can by splitting the string. the [..] operator lets you access object properties by name (and array items index). In a case of nested objects, you simply access them one after the other.
Try like this:
var person = {
name: 'Joe',
contact: {
phone: '555'
}
}
var nameOfPerson = person['name']; //Joe
var str = 'contact.phone';
var phoneToPerson = str.split('.').reduce(function(o, key) {
return o[key];
}, person);
alert(phoneToPerson);

try
var select = "contact.phone";
var value = person;
select.split(".").forEach(function(val){
value = value[val];
});
console.log(value);

Natively, no. However there are way to do it, like splitting the string by . and recursively descend from the person object. It's also possible by evaluating the full string in eval or new Function, but I highly discourage for security reasons.

I know this post is quite old but its strange I can't see very popular "Lodash" solution here which allows to get object nested properties safely.
Example:
var object = {
a: [
{
b: {
c: 3
}
}
]
};
_.get(object, 'a[0].b.c'); // → 3
For your example:
var person = {
name: 'Joe',
contact: {
phone: '555'
}
}
var personPhoneProp = 'contact.phone';
_.get(person, personPhoneProp); // -> '555'
Documentation: https://lodash.com/docs#get

Related

javascript map(val , index) , which condition val is variable and string [duplicate]

This question already has answers here:
Accessing an object property with a dynamically-computed name
(19 answers)
Closed 4 months ago.
I'm pulling items out of the DOM with jQuery and want to set a property on an object using the id of the DOM element.
Example
const obj = {}
jQuery(itemsFromDom).each(function() {
const element = jQuery(this)
const name = element.attr('id')
const value = element.attr('value')
// Here is the problem
obj.name = value
})
If itemsFromDom includes an element with an id of "myId", I want obj to have a property named "myId". The above gives me name.
How do I name a property of an object using a variable using JavaScript?

You can use this equivalent syntax:
obj[name] = value
Example:
let obj = {};
obj["the_key"] = "the_value";
or with ES6 features:
let key = "the_key";
let obj = {
[key]: "the_value",
};
in both examples, console.log(obj) will return: { the_key: 'the_value' }

With ECMAScript 2015 you can do it directly in object declaration using bracket notation:
var obj = {
[key]: value
}
Where key can be any sort of expression (e.g. a variable) returning a value:
var obj = {
['hello']: 'World',
[x + 2]: 42,
[someObject.getId()]: someVar
}

You can even make List of objects like this
var feeTypeList = [];
$('#feeTypeTable > tbody > tr').each(function (i, el) {
var feeType = {};
var $ID = $(this).find("input[id^=txtFeeType]").attr('id');
feeType["feeTypeID"] = $('#ddlTerm').val();
feeType["feeTypeName"] = $('#ddlProgram').val();
feeType["feeTypeDescription"] = $('#ddlBatch').val();
feeTypeList.push(feeType);
});

There are two different notations to access object properties
Dot notation: myObj.prop1
Bracket notation: myObj["prop1"]
Dot notation is fast and easy but you must use the actual property name explicitly. No substitution, variables, etc.
Bracket notation is open ended. It uses a string but you can produce the string using any legal js code. You may specify the string as literal (though in this case dot notation would read easier) or use a variable or calculate in some way.
So, these all set the myObj property named prop1 to the value Hello:
// quick easy-on-the-eye dot notation
myObj.prop1 = "Hello";
// brackets+literal
myObj["prop1"] = "Hello";
// using a variable
var x = "prop1";
myObj[x] = "Hello";
// calculate the accessor string in some weird way
var numList = [0,1,2];
myObj[ "prop" + numList[1] ] = "Hello";
Pitfalls:
myObj.[xxxx] = "Hello"; // wrong: mixed notations, syntax fail
myObj[prop1] = "Hello"; // wrong: this expects a variable called prop1
tl;dnr: If you want to compute or reference the key you must use bracket notation. If you are using the key explicitly, then use dot notation for simple clear code.
Note: there are some other good and correct answers but I personally found them a bit brief coming from a low familiarity with JS on-the-fly quirkiness. This might be useful to some people.

With lodash, you can create new object like this _.set:
obj = _.set({}, key, val);
Or you can set to existing object like this:
var existingObj = { a: 1 };
_.set(existingObj, 'a', 5); // existingObj will be: { a: 5 }
You should take care if you want to use dot (".") in your path, because lodash can set hierarchy, for example:
_.set({}, "a.b.c", "d"); // { "a": { "b": { "c": "d" } } }

First we need to define key as variable and then we need to assign as key as object., for example
var data = {key:'dynamic_key',value:'dynamic_value'}
var key = data.key;
var obj = { [key]: data.value}
console.log(obj)

Related to the subject, not specifically for jquery though. I used this in ec6 react projects, maybe helps someone:
this.setState({ [`${name}`]: value}, () => {
console.log("State updated: ", JSON.stringify(this.state[name]));
});
PS: Please mind the quote character.

With the advent of ES2015 Object.assign and computed property names the OP's code boils down to:
var obj = Object.assign.apply({}, $(itemsFromDom).map((i, el) => ({[el.id]: el.value})));

ajavascript have two type of annotation for fetching javascript Object properties:
Obj = {};
1) (.) annotation eg. Obj.id
this will only work if the object already have a property with name 'id'
2) ([]) annotation eg . Obj[id] here if the object does not have any property with name 'id',it will create a new property with name 'id'.
so for below example:
A new property will be created always when you write Obj[name].
And if the property already exist with the same name it will override it.
const obj = {}
jQuery(itemsFromDom).each(function() {
const element = jQuery(this)
const name = element.attr('id')
const value = element.attr('value')
// This will work
obj[name]= value;
})

If you want to add fields to an object dynamically, simplest way to do it is as follows:
let params = [
{ key: "k1", value: 1 },
{ key: "k2", value: 2 },
{ key: "k3", value: 3 },
];
let data = {};
for (let i = 0; i < params.length; i++) {
data[params[i].key] = params[i].value;
}
console.log(data); // -> { k1: 1, k2: 2, k3: 3 }

The 3 ways to access the object value
We can output the object value by passing in the appropriate key. Because I used emoji as the key in my example, it's a bit tricky. So let's look at a easier example.
let me = {
name: 'samantha',
};
// 1. Dot notation
me.name; // samantha
// 2. Bracket notation (string key)
me['name']; // samantha
// 3. Bracket notation (variable key)
let key = 'name';
me[key]; // samantha
know more

If you have object, you can make array of keys, than map through, and create new object from previous object keys, and values.
Object.keys(myObject)
.map(el =>{
const obj = {};
obj[el]=myObject[el].code;
console.log(obj);
});

objectname.newProperty = value;

const data = [{
name: 'BMW',
value: '25641'
}, {
name: 'Apple',
value: '45876'
},
{
name: 'Benz',
value: '65784'
},
{
name: 'Toyota',
value: '254'
}
]
const obj = {
carsList: [{
name: 'Ford',
value: '47563'
}, {
name: 'Toyota',
value: '254'
}],
pastriesList: [],
fruitsList: [{
name: 'Apple',
value: '45876'
}, {
name: 'Pineapple',
value: '84523'
}]
}
let keys = Object.keys(obj);
result = {};
for(key of keys){
let a = [...data,...obj[key]];
result[key] = a;
}

What does this bracket mean in typescript [duplicate]

This question already has answers here:
Accessing an object property with a dynamically-computed name
(19 answers)
Closed 4 months ago.
I'm pulling items out of the DOM with jQuery and want to set a property on an object using the id of the DOM element.
Example
const obj = {}
jQuery(itemsFromDom).each(function() {
const element = jQuery(this)
const name = element.attr('id')
const value = element.attr('value')
// Here is the problem
obj.name = value
})
If itemsFromDom includes an element with an id of "myId", I want obj to have a property named "myId". The above gives me name.
How do I name a property of an object using a variable using JavaScript?

You can use this equivalent syntax:
obj[name] = value
Example:
let obj = {};
obj["the_key"] = "the_value";
or with ES6 features:
let key = "the_key";
let obj = {
[key]: "the_value",
};
in both examples, console.log(obj) will return: { the_key: 'the_value' }

With ECMAScript 2015 you can do it directly in object declaration using bracket notation:
var obj = {
[key]: value
}
Where key can be any sort of expression (e.g. a variable) returning a value:
var obj = {
['hello']: 'World',
[x + 2]: 42,
[someObject.getId()]: someVar
}

You can even make List of objects like this
var feeTypeList = [];
$('#feeTypeTable > tbody > tr').each(function (i, el) {
var feeType = {};
var $ID = $(this).find("input[id^=txtFeeType]").attr('id');
feeType["feeTypeID"] = $('#ddlTerm').val();
feeType["feeTypeName"] = $('#ddlProgram').val();
feeType["feeTypeDescription"] = $('#ddlBatch').val();
feeTypeList.push(feeType);
});

There are two different notations to access object properties
Dot notation: myObj.prop1
Bracket notation: myObj["prop1"]
Dot notation is fast and easy but you must use the actual property name explicitly. No substitution, variables, etc.
Bracket notation is open ended. It uses a string but you can produce the string using any legal js code. You may specify the string as literal (though in this case dot notation would read easier) or use a variable or calculate in some way.
So, these all set the myObj property named prop1 to the value Hello:
// quick easy-on-the-eye dot notation
myObj.prop1 = "Hello";
// brackets+literal
myObj["prop1"] = "Hello";
// using a variable
var x = "prop1";
myObj[x] = "Hello";
// calculate the accessor string in some weird way
var numList = [0,1,2];
myObj[ "prop" + numList[1] ] = "Hello";
Pitfalls:
myObj.[xxxx] = "Hello"; // wrong: mixed notations, syntax fail
myObj[prop1] = "Hello"; // wrong: this expects a variable called prop1
tl;dnr: If you want to compute or reference the key you must use bracket notation. If you are using the key explicitly, then use dot notation for simple clear code.
Note: there are some other good and correct answers but I personally found them a bit brief coming from a low familiarity with JS on-the-fly quirkiness. This might be useful to some people.

With lodash, you can create new object like this _.set:
obj = _.set({}, key, val);
Or you can set to existing object like this:
var existingObj = { a: 1 };
_.set(existingObj, 'a', 5); // existingObj will be: { a: 5 }
You should take care if you want to use dot (".") in your path, because lodash can set hierarchy, for example:
_.set({}, "a.b.c", "d"); // { "a": { "b": { "c": "d" } } }

First we need to define key as variable and then we need to assign as key as object., for example
var data = {key:'dynamic_key',value:'dynamic_value'}
var key = data.key;
var obj = { [key]: data.value}
console.log(obj)

Related to the subject, not specifically for jquery though. I used this in ec6 react projects, maybe helps someone:
this.setState({ [`${name}`]: value}, () => {
console.log("State updated: ", JSON.stringify(this.state[name]));
});
PS: Please mind the quote character.

With the advent of ES2015 Object.assign and computed property names the OP's code boils down to:
var obj = Object.assign.apply({}, $(itemsFromDom).map((i, el) => ({[el.id]: el.value})));

ajavascript have two type of annotation for fetching javascript Object properties:
Obj = {};
1) (.) annotation eg. Obj.id
this will only work if the object already have a property with name 'id'
2) ([]) annotation eg . Obj[id] here if the object does not have any property with name 'id',it will create a new property with name 'id'.
so for below example:
A new property will be created always when you write Obj[name].
And if the property already exist with the same name it will override it.
const obj = {}
jQuery(itemsFromDom).each(function() {
const element = jQuery(this)
const name = element.attr('id')
const value = element.attr('value')
// This will work
obj[name]= value;
})

If you want to add fields to an object dynamically, simplest way to do it is as follows:
let params = [
{ key: "k1", value: 1 },
{ key: "k2", value: 2 },
{ key: "k3", value: 3 },
];
let data = {};
for (let i = 0; i < params.length; i++) {
data[params[i].key] = params[i].value;
}
console.log(data); // -> { k1: 1, k2: 2, k3: 3 }

The 3 ways to access the object value
We can output the object value by passing in the appropriate key. Because I used emoji as the key in my example, it's a bit tricky. So let's look at a easier example.
let me = {
name: 'samantha',
};
// 1. Dot notation
me.name; // samantha
// 2. Bracket notation (string key)
me['name']; // samantha
// 3. Bracket notation (variable key)
let key = 'name';
me[key]; // samantha
know more

If you have object, you can make array of keys, than map through, and create new object from previous object keys, and values.
Object.keys(myObject)
.map(el =>{
const obj = {};
obj[el]=myObject[el].code;
console.log(obj);
});

objectname.newProperty = value;

const data = [{
name: 'BMW',
value: '25641'
}, {
name: 'Apple',
value: '45876'
},
{
name: 'Benz',
value: '65784'
},
{
name: 'Toyota',
value: '254'
}
]
const obj = {
carsList: [{
name: 'Ford',
value: '47563'
}, {
name: 'Toyota',
value: '254'
}],
pastriesList: [],
fruitsList: [{
name: 'Apple',
value: '45876'
}, {
name: 'Pineapple',
value: '84523'
}]
}
let keys = Object.keys(obj);
result = {};
for(key of keys){
let a = [...data,...obj[key]];
result[key] = a;
}

JavaScript: Fetch Headers: Object literal does not add custom header, new Header() obj does [duplicate]

This question already has answers here:
Accessing an object property with a dynamically-computed name
(19 answers)
Closed 4 months ago.
I'm pulling items out of the DOM with jQuery and want to set a property on an object using the id of the DOM element.
Example
const obj = {}
jQuery(itemsFromDom).each(function() {
const element = jQuery(this)
const name = element.attr('id')
const value = element.attr('value')
// Here is the problem
obj.name = value
})
If itemsFromDom includes an element with an id of "myId", I want obj to have a property named "myId". The above gives me name.
How do I name a property of an object using a variable using JavaScript?

You can use this equivalent syntax:
obj[name] = value
Example:
let obj = {};
obj["the_key"] = "the_value";
or with ES6 features:
let key = "the_key";
let obj = {
[key]: "the_value",
};
in both examples, console.log(obj) will return: { the_key: 'the_value' }

With ECMAScript 2015 you can do it directly in object declaration using bracket notation:
var obj = {
[key]: value
}
Where key can be any sort of expression (e.g. a variable) returning a value:
var obj = {
['hello']: 'World',
[x + 2]: 42,
[someObject.getId()]: someVar
}

You can even make List of objects like this
var feeTypeList = [];
$('#feeTypeTable > tbody > tr').each(function (i, el) {
var feeType = {};
var $ID = $(this).find("input[id^=txtFeeType]").attr('id');
feeType["feeTypeID"] = $('#ddlTerm').val();
feeType["feeTypeName"] = $('#ddlProgram').val();
feeType["feeTypeDescription"] = $('#ddlBatch').val();
feeTypeList.push(feeType);
});

There are two different notations to access object properties
Dot notation: myObj.prop1
Bracket notation: myObj["prop1"]
Dot notation is fast and easy but you must use the actual property name explicitly. No substitution, variables, etc.
Bracket notation is open ended. It uses a string but you can produce the string using any legal js code. You may specify the string as literal (though in this case dot notation would read easier) or use a variable or calculate in some way.
So, these all set the myObj property named prop1 to the value Hello:
// quick easy-on-the-eye dot notation
myObj.prop1 = "Hello";
// brackets+literal
myObj["prop1"] = "Hello";
// using a variable
var x = "prop1";
myObj[x] = "Hello";
// calculate the accessor string in some weird way
var numList = [0,1,2];
myObj[ "prop" + numList[1] ] = "Hello";
Pitfalls:
myObj.[xxxx] = "Hello"; // wrong: mixed notations, syntax fail
myObj[prop1] = "Hello"; // wrong: this expects a variable called prop1
tl;dnr: If you want to compute or reference the key you must use bracket notation. If you are using the key explicitly, then use dot notation for simple clear code.
Note: there are some other good and correct answers but I personally found them a bit brief coming from a low familiarity with JS on-the-fly quirkiness. This might be useful to some people.

With lodash, you can create new object like this _.set:
obj = _.set({}, key, val);
Or you can set to existing object like this:
var existingObj = { a: 1 };
_.set(existingObj, 'a', 5); // existingObj will be: { a: 5 }
You should take care if you want to use dot (".") in your path, because lodash can set hierarchy, for example:
_.set({}, "a.b.c", "d"); // { "a": { "b": { "c": "d" } } }

First we need to define key as variable and then we need to assign as key as object., for example
var data = {key:'dynamic_key',value:'dynamic_value'}
var key = data.key;
var obj = { [key]: data.value}
console.log(obj)

Related to the subject, not specifically for jquery though. I used this in ec6 react projects, maybe helps someone:
this.setState({ [`${name}`]: value}, () => {
console.log("State updated: ", JSON.stringify(this.state[name]));
});
PS: Please mind the quote character.

With the advent of ES2015 Object.assign and computed property names the OP's code boils down to:
var obj = Object.assign.apply({}, $(itemsFromDom).map((i, el) => ({[el.id]: el.value})));

ajavascript have two type of annotation for fetching javascript Object properties:
Obj = {};
1) (.) annotation eg. Obj.id
this will only work if the object already have a property with name 'id'
2) ([]) annotation eg . Obj[id] here if the object does not have any property with name 'id',it will create a new property with name 'id'.
so for below example:
A new property will be created always when you write Obj[name].
And if the property already exist with the same name it will override it.
const obj = {}
jQuery(itemsFromDom).each(function() {
const element = jQuery(this)
const name = element.attr('id')
const value = element.attr('value')
// This will work
obj[name]= value;
})

If you want to add fields to an object dynamically, simplest way to do it is as follows:
let params = [
{ key: "k1", value: 1 },
{ key: "k2", value: 2 },
{ key: "k3", value: 3 },
];
let data = {};
for (let i = 0; i < params.length; i++) {
data[params[i].key] = params[i].value;
}
console.log(data); // -> { k1: 1, k2: 2, k3: 3 }

The 3 ways to access the object value
We can output the object value by passing in the appropriate key. Because I used emoji as the key in my example, it's a bit tricky. So let's look at a easier example.
let me = {
name: 'samantha',
};
// 1. Dot notation
me.name; // samantha
// 2. Bracket notation (string key)
me['name']; // samantha
// 3. Bracket notation (variable key)
let key = 'name';
me[key]; // samantha
know more

If you have object, you can make array of keys, than map through, and create new object from previous object keys, and values.
Object.keys(myObject)
.map(el =>{
const obj = {};
obj[el]=myObject[el].code;
console.log(obj);
});

objectname.newProperty = value;

const data = [{
name: 'BMW',
value: '25641'
}, {
name: 'Apple',
value: '45876'
},
{
name: 'Benz',
value: '65784'
},
{
name: 'Toyota',
value: '254'
}
]
const obj = {
carsList: [{
name: 'Ford',
value: '47563'
}, {
name: 'Toyota',
value: '254'
}],
pastriesList: [],
fruitsList: [{
name: 'Apple',
value: '45876'
}, {
name: 'Pineapple',
value: '84523'
}]
}
let keys = Object.keys(obj);
result = {};
for(key of keys){
let a = [...data,...obj[key]];
result[key] = a;
}

Update Javascript Object only if there is a change [duplicate]

This question already has answers here:
How to determine equality for two JavaScript objects?
(82 answers)
Closed 2 years ago.
I have a javascript object on my DB, its personal data, this is the structure:
const storedUserData = {
name: "John",
sirname:"Doe",
phone: "666-666-66666",
streetName: "Fake Street",
streetNumber: "123",
zipCode: "90125"
}
and I have a separate object, which has the same structure, which basically is on the front end, and its the result of reading form data.
const formData = {
name: "John",
sirname:"Doe",
phone: "666-666-66666",
streetName: "Fake Street",
streetNumber: "123",
zipCode: "90125"
}
Basically, when the user clicks submit I want to check if there are differences between the stored object storedUserData, above, and the new object, formData. If there are differences, save the differences to the DB.
Of course, I could go on like this for each property, since there are few:
if(storedUserData.name !== formData.name) {
pushDataToDb()
}
but its the lazy approach, and I want to do it correctly. I've been reading into object keys, but I cant figure it out. How could I successfully loop between each property of both items comparing them, and then only if there is a change between the two properties I would push to DB.
Thank you.

You could use a loop as you mentioned above,
function isEquivalent(a, b) {
// Create arrays of property names
var aProps = Object.getOwnPropertyNames(a);
var bProps = Object.getOwnPropertyNames(b);
// If number of properties is different,
// objects are not equivalent
if (aProps.length != bProps.length) {
return false;
}
for (var i = 0; i < aProps.length; i++) {
var propName = aProps[i];
// If values of same property are not equal,
// objects are not equivalent
if (a[propName] !== b[propName]) {
return false;
}
}
// If we made it this far, objects
// are considered equivalent
return true;
}
Read more about it here

Add a property to a JavaScript object using a variable as the name? [duplicate]

This question already has answers here:
Accessing an object property with a dynamically-computed name
(19 answers)
Closed 4 months ago.
I'm pulling items out of the DOM with jQuery and want to set a property on an object using the id of the DOM element.
Example
const obj = {}
jQuery(itemsFromDom).each(function() {
const element = jQuery(this)
const name = element.attr('id')
const value = element.attr('value')
// Here is the problem
obj.name = value
})
If itemsFromDom includes an element with an id of "myId", I want obj to have a property named "myId". The above gives me name.
How do I name a property of an object using a variable using JavaScript?

You can use this equivalent syntax:
obj[name] = value
Example:
let obj = {};
obj["the_key"] = "the_value";
or with ES6 features:
let key = "the_key";
let obj = {
[key]: "the_value",
};
in both examples, console.log(obj) will return: { the_key: 'the_value' }

With ECMAScript 2015 you can do it directly in object declaration using bracket notation:
var obj = {
[key]: value
}
Where key can be any sort of expression (e.g. a variable) returning a value:
var obj = {
['hello']: 'World',
[x + 2]: 42,
[someObject.getId()]: someVar
}

You can even make List of objects like this
var feeTypeList = [];
$('#feeTypeTable > tbody > tr').each(function (i, el) {
var feeType = {};
var $ID = $(this).find("input[id^=txtFeeType]").attr('id');
feeType["feeTypeID"] = $('#ddlTerm').val();
feeType["feeTypeName"] = $('#ddlProgram').val();
feeType["feeTypeDescription"] = $('#ddlBatch').val();
feeTypeList.push(feeType);
});

There are two different notations to access object properties
Dot notation: myObj.prop1
Bracket notation: myObj["prop1"]
Dot notation is fast and easy but you must use the actual property name explicitly. No substitution, variables, etc.
Bracket notation is open ended. It uses a string but you can produce the string using any legal js code. You may specify the string as literal (though in this case dot notation would read easier) or use a variable or calculate in some way.
So, these all set the myObj property named prop1 to the value Hello:
// quick easy-on-the-eye dot notation
myObj.prop1 = "Hello";
// brackets+literal
myObj["prop1"] = "Hello";
// using a variable
var x = "prop1";
myObj[x] = "Hello";
// calculate the accessor string in some weird way
var numList = [0,1,2];
myObj[ "prop" + numList[1] ] = "Hello";
Pitfalls:
myObj.[xxxx] = "Hello"; // wrong: mixed notations, syntax fail
myObj[prop1] = "Hello"; // wrong: this expects a variable called prop1
tl;dnr: If you want to compute or reference the key you must use bracket notation. If you are using the key explicitly, then use dot notation for simple clear code.
Note: there are some other good and correct answers but I personally found them a bit brief coming from a low familiarity with JS on-the-fly quirkiness. This might be useful to some people.

With lodash, you can create new object like this _.set:
obj = _.set({}, key, val);
Or you can set to existing object like this:
var existingObj = { a: 1 };
_.set(existingObj, 'a', 5); // existingObj will be: { a: 5 }
You should take care if you want to use dot (".") in your path, because lodash can set hierarchy, for example:
_.set({}, "a.b.c", "d"); // { "a": { "b": { "c": "d" } } }

First we need to define key as variable and then we need to assign as key as object., for example
var data = {key:'dynamic_key',value:'dynamic_value'}
var key = data.key;
var obj = { [key]: data.value}
console.log(obj)

Related to the subject, not specifically for jquery though. I used this in ec6 react projects, maybe helps someone:
this.setState({ [`${name}`]: value}, () => {
console.log("State updated: ", JSON.stringify(this.state[name]));
});
PS: Please mind the quote character.

With the advent of ES2015 Object.assign and computed property names the OP's code boils down to:
var obj = Object.assign.apply({}, $(itemsFromDom).map((i, el) => ({[el.id]: el.value})));

ajavascript have two type of annotation for fetching javascript Object properties:
Obj = {};
1) (.) annotation eg. Obj.id
this will only work if the object already have a property with name 'id'
2) ([]) annotation eg . Obj[id] here if the object does not have any property with name 'id',it will create a new property with name 'id'.
so for below example:
A new property will be created always when you write Obj[name].
And if the property already exist with the same name it will override it.
const obj = {}
jQuery(itemsFromDom).each(function() {
const element = jQuery(this)
const name = element.attr('id')
const value = element.attr('value')
// This will work
obj[name]= value;
})

If you want to add fields to an object dynamically, simplest way to do it is as follows:
let params = [
{ key: "k1", value: 1 },
{ key: "k2", value: 2 },
{ key: "k3", value: 3 },
];
let data = {};
for (let i = 0; i < params.length; i++) {
data[params[i].key] = params[i].value;
}
console.log(data); // -> { k1: 1, k2: 2, k3: 3 }

The 3 ways to access the object value
We can output the object value by passing in the appropriate key. Because I used emoji as the key in my example, it's a bit tricky. So let's look at a easier example.
let me = {
name: 'samantha',
};
// 1. Dot notation
me.name; // samantha
// 2. Bracket notation (string key)
me['name']; // samantha
// 3. Bracket notation (variable key)
let key = 'name';
me[key]; // samantha
know more

If you have object, you can make array of keys, than map through, and create new object from previous object keys, and values.
Object.keys(myObject)
.map(el =>{
const obj = {};
obj[el]=myObject[el].code;
console.log(obj);
});

objectname.newProperty = value;

const data = [{
name: 'BMW',
value: '25641'
}, {
name: 'Apple',
value: '45876'
},
{
name: 'Benz',
value: '65784'
},
{
name: 'Toyota',
value: '254'
}
]
const obj = {
carsList: [{
name: 'Ford',
value: '47563'
}, {
name: 'Toyota',
value: '254'
}],
pastriesList: [],
fruitsList: [{
name: 'Apple',
value: '45876'
}, {
name: 'Pineapple',
value: '84523'
}]
}
let keys = Object.keys(obj);
result = {};
for(key of keys){
let a = [...data,...obj[key]];
result[key] = a;
}

Develop Reference

JavaScript is the programming language of the Web.

Access a nested property with a string [duplicate] - javascript

try var select = "contact.phone"; var value = person; select.split(".").forEach(function(val){ value = value[val]; }); console.log(value);

Natively, no. However there are way to do it, like splitting the string by . and recursively descend from the person object. It's also possible by evaluating the full string in eval or new Function, but I highly discourage for security reasons.

Related

javascript map(val , index) , which condition val is variable and string [duplicate]

What does this bracket mean in typescript [duplicate]

JavaScript: Fetch Headers: Object literal does not add custom header, new Header() obj does [duplicate]

Update Javascript Object only if there is a change [duplicate]

Add a property to a JavaScript object using a variable as the name? [duplicate]

Categories

Resources