How to get value in an object's key using a variable referencing that key?
JavascriptJavascript Problem Overview
I have an object and I can reference key a
as in the following:
var obj = {
a: "A",
b: "B",
c: "C"
}
console.log(obj.a); // return string : A
I want to get the value by using a variable to reference the object key as below:
var name = "a";
console.log(obj.name) // this prints undefined, but I want it to print "A"
How can I do this?
Javascript Solutions
Solution 1 - Javascript
Use []
notation for string representations of properties:
console.log(obj[name]);
Otherwise it's looking for the "name" property, rather than the "a" property.
Solution 2 - Javascript
obj["a"]
is equivalent to obj.a
so use obj[name]
you get "A"
Solution 3 - Javascript
Use this syntax:
obj[name]
Note that obj.x
is the same as obj["x"]
for all valid JS identifiers, but the latter form accepts all string as keys (not just valid identifiers).
obj["Hey, this is ... neat?"] = 42
Solution 4 - Javascript
You can get value
of key
like this...
var obj = {
a: "A",
b: "B",
c: "C"
};
console.log(obj.a);
console.log(obj['a']);
name = "a";
console.log(obj[name])
Solution 5 - Javascript
I use the following syntax:
objTest = {"error": true, "message": "test message"};
get error:
var name = "error"
console.log(objTest[name]);
get message:
name = "message"
console.log(objTest[name]);
Solution 6 - Javascript
https://jsfiddle.net/sudheernunna/tug98nfm/1/
var days = {};
days["monday"] = true;
days["tuesday"] = true;
days["wednesday"] = false;
days["thursday"] = true;
days["friday"] = false;
days["saturday"] = true;
days["sunday"] = false;
var userfalse=0,usertrue=0;
for(value in days)
{
if(days[value]){
usertrue++;
}else{
userfalse++;
}
console.log(days[value]);
}
alert("false",userfalse);
alert("true",usertrue);
Solution 7 - Javascript
var o = { cat : "meow", dog : "woof"};
var x = Object.keys(o);
for (i=0; i<x.length; i++) {
console.log(o[x[i]]);
}
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