This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
javascript object, access variable property name?
I am messing around with JS, learning a stuff and I am wondering about something...
Say you have a function aFunc(), and you accept a string aFunc(val). The value is user defined and is then used to modify the CSS of an element.
For Example:
function aFunc(val){
document.getElementById('something').style.val = 'red';
}
Say the user entered borderColor, it would somehow refrence borderColor where val is. I do not know how or if this is possible.
EDIT:
Please no eval() :)
Just use this as a base: JSBIN- Demo on a Div
var type = prompt("style");
var value = prompt("value");
document.body.style[type] = value;
Every object in JavaScript has a method called hasOwnProperty which takes a string value and will return a Boolean value.
var myObj = {
name: "Josh"
};
myObj.hasOwnProperty("name") === true; //This is true
You can use that to test for the presence of a particular property and then use the method stated in Akhil Sekharan's answer to access that property.
Related
This question already has answers here:
How to execute a JavaScript function when I have its name as a string
(36 answers)
Closed 2 years ago.
My problem is simple and I couldn't find the proper answer in this forum. My bad...
I want to do that :
const dataReceived = foo;
foo(state);
How can I do that?
I read it is better to avoid eval, and I couldn't get success with new Function.
Thanks for your help!
EDIT
Thanks for your answers.
I work with React.
In my reducer, I have a create_item case.
I can reach action.category, that can be the word 'currency' or 'country'.
What I want to do is to launch either the method createCurrency or createCountry according what is inside action.category.
That's why I tried to join 'create' and 'action.category' to create a dynamic function name.
But it seems to be a poor idea...
The simplest approach is to create an object which contains an entry where:
the key is a string
the value is a function.
Example:
const myObject = {
myFunction: () => { [... DO SOMETHING...] }
}
Subsequently you will be able to invoke the function, using:
myObject.myFunction();
The above becomes more powerful when you use brackets notation.
Example:
const myString = 'myFunction';
myObject[myString]();
This question already has answers here:
Is it possible to add dynamically named properties to JavaScript object?
(20 answers)
Closed 2 years ago.
I have looked all over google and i have found nothing that fits my needs. How would you add an item to an object. I basically have a string variable that i want as the key. Therefore i cant use obj.key = 'something';. I sort of want it like:
obj = {'somekey': 'somevalue'};
obj.add('someotherkey': 'someothervalue');
console.log(obj);
by obj.add() i mean someone's solution
and then console says {'somekey': 'somevalue', 'someotherkey': 'someothervalue'}
Does anyone know a way to do this. I don't care at what position it is just whether it is there. By the way i'm using node if that helps. If you have any questions on my code please ask.
Very simple:
obj["somekey"] = "somevalue";
You can also use a variable instead:
let myVariable = "somekey";
obj[myVariable] = "somevalue";
Or you just use normal object notation:
obj.somekey = "somevalue"
This question already has an answer here:
How do I access an object property dynamically using a variable in JavaScript?
(1 answer)
Closed 5 years ago.
Testing my ability to write code in JavaScript and Node (perhaps a bit of a monumental effort) and also attempting to understand standards.
I want to dynamically change an attribute in an object as in this examnple:
var parms = {
host:'',
port:'',
user:'',
pass:''
};
parms.user='foo';
parms.pass='bar';
console.log(parms.user);
setParm = function(param,value){
parms.param = value;
}
setParm('user','baz');
console.log(parms.user);
However, I'm completely blind. I feel as though I may be in a blind alley in terms of what I think is possible versus what is actually workable.
You are passing the property as a string, so accessing with . won't work. One solution I know is that you can use dict-like indexing:
var parms = {
host:'',
port:'',
user:'',
pass:''
};
parms.user='foo';
parms.pass='bar';
console.log(parms.user);
setParm = function(param,value){
parms[param] = value;
}
setParm('user','baz');
console.log(parms.user);
This question already has answers here:
Convert string to variable name in JavaScript
(11 answers)
Closed 6 years ago.
Apologies if this is simple. I just couldn't figure-out how to do it. Searched on this site on how to dynamically change variables and evaluate them etc but can't figure out how to do what I want.
Problem: I have a variable that I set to a value:
vm.toggleDrop = function($switchToggle){
vm.switchValue = "switch"+$switchToggle;
//Here
};
Where it says "Here", I need to instantiate a new variable that is called whatever is the result if the above statement eg; switch1 then set it true or false as a boolean. eg: switch1 = false;
Therefore again, if $switchToggle parameter was "Test", I need to dynamically create a variable called switchTest and set it true or false.
Is such a thing possible ?
Thanks all
Something like that?(I created vm variable just for code snippet, ignore it)
var vm = {};
vm.toggleDrop = function($switchToggle){
vm.switchValue = "switch"+$switchToggle;
vm[vm.switchValue] = 'whatever';
console.log(vm);
};
vm.toggleDrop('true');
Also if you do not need to attach variable to vm object, best answer will be #nastyklad provided(using window[vm.switchValue]
Something like this:
function setVariable(name){
var variableName = 'switch' + name;
vm[variableName] = true;
}
This question already has an answer here:
Accessing a JSON property (String) using a variable
(1 answer)
Closed 8 years ago.
I want to use a string as a JSON property in JavaScript.
var knights = {
'phrases': 'Ni!'
};
var x = 'phrases';
console.log(knights.x); // Doesn't log "Ni!"
When I run this code, it obviously doesn't work because it interprets "x" and not the contents of the variable "x".
The full code in context on pastebin: http://pastebin.com/bMQJ9EDf
Is there an easy solution to this?
knights.x looks for a property named x. You want knights[x], which is equivalent to knights['phrases'] == knights.phrases.
Full code (fixing a couple of typos in your example):
var knights = {
"phrases": "Ni!"
};
var x = 'phrases';
console.log(knights[x]); // logs Ni!
Try this to access using variables having string values
kinghts[x]
Basically this is trick
kinghts[x]==knighted["phrases"]==knighted.phrases.
knights.x will get a key named x, So it'll return undefined here.
knights.x is the same as knights['x'] - retrieving a property under the key x. It's not accessing the variable x and substituting in the value. Instead, you want knights[x] which is the equivalent of knights['phrases']