This question already has answers here:
create object using variables for property name [duplicate]
(4 answers)
Closed 8 years ago.
I have
object.name = 'foo';
var value = 'bar';
...
var params = { object.name : 1, value : value};
I want a result equivalent to
var params = { foo : 1, value : bar };
what can I do?
Objects are sometimes called associative arrays, since each property is associated with a `string value that can be used to access it.
Try using [] to set object property -
object.name = 'foo';
var value = 'bar';
var params = { value:value};
params[ object.name] = 1;
Output:- {value: "bar", foo: 1}
Related
This question already has answers here:
Why can't a property be added to a null value?
(2 answers)
Closed 6 years ago.
property myProperty is not assigned to variable foo, foo is an object.
var foo=null;//null is an object
foo.myProperty = "my value";
console.log(typeof foo.myProperty);
A Javascript object should be declared like this
var myObject = {};
Try to modify you code like
var foo = {};
foo.myProperty = "a string";
console.log(typeof foo.myProperty);
This question already has answers here:
Add a property to a JavaScript object using a variable as the name? [duplicate]
(14 answers)
Closed 7 years ago.
I want to add a new property to 'myObj', name it 'string1' and give it a value of 'string2', but when I do it it returns 'undefined:
var myObj = new Object;
var a = 'string1';
var b = 'string2';
myObj.a = b;
alert(myObj.string1); //Returns 'undefined'
alert(myObj.a); //Returns 'string2'
In other words: How do I create an object property and give it the name stored in the variable, but not the name of the variable itself?
There's the dot notation and the bracket notation
myObj[a] = b;
ES6 introduces computed property names, which allow you to do
var myObj = {[a]: b};
Dot notation and the properties are equivalent. So you would accomplish like so:
// const myObj = new Object();
const myObj = {};
const a = 'string1';
myObj[a] = 'whatever';
alert(myObj.string1);
(alerts "whatever")
Ecu, if you do myObj.a, then it looks for the property named a of myObj.
If you do myObj[a] =b then it looks for the a.valueOf() property of myObj.
Oneliner:
obj = (function(attr, val){ var a = {}; a[attr]=val; return a; })('hash', 5);
Or:
attr = 'hash';
val = 5;
var obj = (obj={}, obj[attr]=val, obj);
Anything shorter?
You could just use this:
function createObject(propName, propValue){
this[propName] = propValue;
}
var myObj1 = new createObject('string1','string2');
Anything you pass as the first parameter will be the property name, and the second parameter is the property value.
You cannot use a variable to access a property via dot notation, instead use the array notation.
var obj= {
'name' : 'jroi'
};
var a = 'name';
alert(obj.a); //will not work
alert(obj[a]); //should work and alert jroi'
As $scope is an object, you can try with JavaScript by:
$scope['something'] = 'hey'
It is equal to:
$scope.something = 'hey'
I created a fiddle to test.
The following demonstrates an alternative approach for returning a key pair object using the form of (a, b). The first example uses the string 'key' as the property name, and 'val' as the value.
Example #1:
(function(o,a,b){return o[a]=b,o})({},'key','val');
Example: #2:
var obj = { foo: 'bar' };
(function(o,a,b){return o[a]=b,o})(obj,'key','val');
As shown in the second example, this can modify existing objects, too (if property is already defined in the object, value will be overwritten).
Result #1: { key: 'val' }
Result #2: { foo: 'bar', key: 'val' }
This question already has answers here:
How to set object property (of object property of..) given its string name in JavaScript?
(16 answers)
Closed 8 years ago.
I've read this existing question on stackoverflow.
My target is to set a property on a "nested Property and set a new Value (without eval!):
What i have is a dynamic string as example : “A.B.C”
And a JSON Object:
var obj ={
A: {
B: {
C: 23
C1: {}
}
}
}
Now i want to access this property and set it:
If the string has a fixed amount of properties i can just write:
obj[prop1][prop2][prop3] = 42
What would be the way to make this dynamic, so when passing “A.B” the object at B is replaced?
Something like this will work..
var str = "A.B.C";
var obj ={
A: {
B: {
C: 23,
C1: {}
}
}
};
updateObj(obj,str,10);
function updateObj(obj,str,val){
var tok = str.split(".");
var update = function(obj, index){
if (index < tok.length){
if ( !obj.hasOwnProperty(tok[index])){
obj[tok[index]] = {};
}
if (index == tok.length-1){
obj[tok[index]] = val;
}
update(obj[tok[index]],++index);
}
}
update(obj,0);
}
console.log(obj);
This question already has answers here:
"Variable" variables in JavaScript
(9 answers)
Closed 7 months ago.
In PHP I can mess around with variable variables and I'm wondering if I can do the same in JavaScript.
I want to create a new object with a property which's name is based on the value of a variable.
if ( obj.name === 'foo' ) {
var data = { foo: value };
}
if ( obj.name === 'bar' ) {
var data = { bar: value };
}
Is there a shorter way of doing this without using eval()? Something like:
var data = { obj.name: value };
Try this:
var data = {};
data[obj.name] = value;
You can read some more about js objects Here.
Objects in JavaScript are simply hash maps. You can access members by indexing with their names. For your problem you can use
var data = {};
data[obj.name] = value;
I've used this to implement a dynamic dispatch mechanism for arithmetic operations on different numerical types as described here.
This question already has answers here:
Add a property to a JavaScript object using a variable as the name? [duplicate]
(14 answers)
Closed 7 years ago.
I want to add a new property to 'myObj', name it 'string1' and give it a value of 'string2', but when I do it it returns 'undefined:
var myObj = new Object;
var a = 'string1';
var b = 'string2';
myObj.a = b;
alert(myObj.string1); //Returns 'undefined'
alert(myObj.a); //Returns 'string2'
In other words: How do I create an object property and give it the name stored in the variable, but not the name of the variable itself?
There's the dot notation and the bracket notation
myObj[a] = b;
ES6 introduces computed property names, which allow you to do
var myObj = {[a]: b};
Dot notation and the properties are equivalent. So you would accomplish like so:
// const myObj = new Object();
const myObj = {};
const a = 'string1';
myObj[a] = 'whatever';
alert(myObj.string1);
(alerts "whatever")
Ecu, if you do myObj.a, then it looks for the property named a of myObj.
If you do myObj[a] =b then it looks for the a.valueOf() property of myObj.
Oneliner:
obj = (function(attr, val){ var a = {}; a[attr]=val; return a; })('hash', 5);
Or:
attr = 'hash';
val = 5;
var obj = (obj={}, obj[attr]=val, obj);
Anything shorter?
You could just use this:
function createObject(propName, propValue){
this[propName] = propValue;
}
var myObj1 = new createObject('string1','string2');
Anything you pass as the first parameter will be the property name, and the second parameter is the property value.
You cannot use a variable to access a property via dot notation, instead use the array notation.
var obj= {
'name' : 'jroi'
};
var a = 'name';
alert(obj.a); //will not work
alert(obj[a]); //should work and alert jroi'
As $scope is an object, you can try with JavaScript by:
$scope['something'] = 'hey'
It is equal to:
$scope.something = 'hey'
I created a fiddle to test.
The following demonstrates an alternative approach for returning a key pair object using the form of (a, b). The first example uses the string 'key' as the property name, and 'val' as the value.
Example #1:
(function(o,a,b){return o[a]=b,o})({},'key','val');
Example: #2:
var obj = { foo: 'bar' };
(function(o,a,b){return o[a]=b,o})(obj,'key','val');
As shown in the second example, this can modify existing objects, too (if property is already defined in the object, value will be overwritten).
Result #1: { key: 'val' }
Result #2: { foo: 'bar', key: 'val' }