This question already has answers here:
"Variable" variables in JavaScript
(9 answers)
Closed 6 years ago.
how would I make an object in javascript with a computed name.
Context:
I am making an add-on that will sit in the browser, log each hostname visited, create an object named after each one. I'm replacing "." with "_"
So for example on this site it would create a stackoverflow_com object.
is this possible?
another example would be
var 1+1 (with the variable actually being 2)
I know brackets make this possible with properies but I don't know how to do it with the name itself.
You need to store them either in a global object (like window) or preferably an object of your choosing
var mySites = {};
mySites["stackoverflow_com"] = "foo"; // access as mySites.stackoverflow_com or mySites["stackoverflow_com"]
mySites[1+1] = "bar"; // access as mySites[2];
More info: JavaScript property access: dot notation vs. brackets?
Related
This question already has answers here:
Dynamic function name in javascript?
(24 answers)
Closed 2 years ago.
I need to define a function with a name that I have in the string.
Not a big deal, right?
window[fnName] = function(...args) {
// ...
}
But what if I cannot access the window object? Like inside of Worker, for example.
Is it possible to do it without window and without eval()?
You can use self. It is property in both window and Worker scope that references back to their global scope. MDN/Window/self
This question already has answers here:
How can I access and process nested objects, arrays, or JSON?
(31 answers)
JavaScript property access: dot notation vs. brackets?
(17 answers)
Closed 8 years ago.
I need to know why this isn't working. My Javascript code accesses a variable in an object. But it appears not to be working, partly because I can't figure out the syntax.
var obj = {
size:"small",
big:false,
thing:true
}
alert(obj[size]);
I'm just not sure if I got the syntax right…
This will work here.
obj.size //returns small
OR
obj["size"] //returns small
OR
var my_var = "size"
obj[my_var] //returns small
You can reference object values either by:
obj["size"]
or
obj.size
However, there is an exception. For instance, if you have following object with a number key: (Note: key is still a string even if it's defined this way):
var obj = {
1: true
};
You can retrieve it's value only by using: obj["1"]
Hence, using obj.1 will cause a syntax error.
Therefore, your code works if you change it to e.g.: alert(obj["size"]); but I prefer to use console.log(obj["size"]); for debugging. At least, if you are playing with node.js as your tags indicates.
Cheers.
This question already has answers here:
JavaScript property access: dot notation vs. brackets?
(17 answers)
Closed 8 years ago.
What does window['someKeyword'] mean in JavaScript?
I guess the window is the DOM window object, but the syntax to retrieve a property is window.propertyName in the reference I found, not window['propertyName']. Are these two ways to retrieve the property?
To access a field of an object in Javascript there are two ways.
let's this is an object
obj = {name:'Object1'};
You can access name field by two ways
obj.name // returns 'Object1'
obj['name'] //returns 'Object1'
besically [] this method is useful when you have to access a field using a variable like bellow
var obj = {name:'Object1'}
var field = 'name'
obj[field] //returns 'Object1' because it will put value of field in `[]`
This question already has answers here:
JavaScript object: access variable property by name as string [duplicate]
(3 answers)
Accessing an object property with a dynamically-computed name
(19 answers)
dynamically select a javascript object attribute
(1 answer)
Closed 8 years ago.
I have a javascript object (named resource) used for translating my texts.
resource
.fileNotFound >> "File not found"
.advSearch >> "Advanced search"
Usually I use this like below:
alert (resource.advSearch);
Now I need to access one of the member of this resource object through a variable.
Example:
var trans = "advSearch";
My question: how can I get the translation in my resource object for 'advSearch' contained in the trans variable?
Thanks.
You need to use the bracket notation instead of dot notation as the member operator
resource[trans]
You can use the [] notation to access properties as well.
resource[trans];
This question already has answers here:
Accessing an object property with a dynamically-computed name
(19 answers)
jquery dynamic id
(4 answers)
Closed 8 years ago.
i need to access
objectName.myID
but the "myID" part is dynamically generated..
how do i do this?
i tried
this['objectName.'+ variable]
i'd hate to use eval...
ps
this happens in a function (local scope) by the way..
You can access Object properties in two ways:
o.propertyname
//or
o.["propertyname"]
When using the bracket notation you have to put the propertyname in quotes or else it will be interpreted as a variable name (which in your case is exactly what you want). So in your case where you have stored the name of the property as a string, the way to go would be:
var variable = "propertyname";
o[variable];
/* /\ variable is replace with it's string representation "propertyname" */
You can even call methods this way:
var o = {};
var functionname = 'toString';
o[functionname]();
You can mix both notations, your example would look like:
var obj = 'objectName';
var prop = 'myID';
this[obj][prop]
// or this is possible too:
this.objectName[prop]
Assuming propertyName is the name of a variable holding the name of the property, for example 'myId', then you can use.
objectName[propertyName]
More details in the MDN : Working with objects