If I have a JS object like:
var foo = { 'bar' : 'baz' }
If I know that foo
has that basic key/value structure, but don't know the name of the key, what's the easiest way to get it? for ... in
? $.each()
? I hope there's something better....
This question is related to
javascript
jquery
use for each loop for accessing keys in Object or Maps in javascript
for(key in foo){
console.log(key);//for key name in your case it will be bar
console.log(foo[key]);// for key value in your case it will be baz
}
Note: you can also use
Object.keys(foo);
it will give you like this output:
[bar];
There is no way other than for ... in
. If you don't want to use that (parhaps because it's marginally inefficient to have to test hasOwnProperty
on each iteration?) then use a different construct, e.g. an array of kvp's:
[{ key: 'key', value: 'value'}, ...]
You can access each key individually without iterating as in:
var obj = { first: 'someVal', second: 'otherVal' };
alert(Object.keys(obj)[0]); // returns first
alert(Object.keys(obj)[1]); // returns second
This is the simplest and easy way. This is how we do this.
var obj = { 'bar' : 'baz' }_x000D_
var key = Object.keys(obj)[0];_x000D_
var value = obj[key];_x000D_
_x000D_
console.log("key = ", key) // bar_x000D_
console.log("value = ", value) // baz
_x000D_
Object.keys(obj) // ['bar']
Now you can iterate on the objects and can access values like below-
Object.keys(obj).forEach( function(key) {
console.log(obj[key]) // baz
})
for showing as a string, simply use:
console.log("they are: " + JSON.stringify(foo));
Since you mentioned $.each()
, here's a handy approach that would work in jQuery 1.6+:
var foo = { key1: 'bar', key2: 'baz' };
// keys will be: ['key1', 'key2']
var keys = $.map(foo, function(item, key) {
return key;
});
You would iterate inside the object with a for loop:
for(var i in foo){
alert(i); // alerts key
alert(foo[i]); //alerts key's value
}
Or
Object.keys(foo)
.forEach(function eachKey(key) {
alert(key); // alerts key
alert(foo[key]); // alerts value
});
// iterate through key-value gracefully
const obj = { a: 5, b: 7, c: 9 };
for (const [key, value] of Object.entries(obj)) {
console.log(`${key} ${value}`); // "a 5", "b 7", "c 9"
}
Refer MDN
Given your Object:
var foo = { 'bar' : 'baz' }
To get bar
, use:
Object.keys(foo)[0]
To get baz
, use:
foo[Object.keys(foo)[0]]
Assuming a single object
I was having the same problem and this is what worked
//example of an Object
var person = {
firstName:"John",
lastName:"Doe",
age:50,
eyeColor:"blue"
};
//How to access a single key or value
var key = Object.keys(person)[0];
var value = person.firstName;
Object.keys() The Object.keys() method returns an array of a given object's own enumerable properties, in the same order as that provided by a for...in loop (the difference being that a for-in loop enumerates properties in the prototype chain as well).
var arr1 = Object.keys(obj);
Object.values() The Object.values() method returns an array of a given object's own enumerable property values, in the same order as that provided by a for...in loop (the difference being that a for-in loop enumerates properties in the prototype chain as well).
var arr2 = Object.values(obj);
For more please go here
A one liner for you:
const OBJECT = {
'key1': 'value1',
'key2': 'value2',
'key3': 'value3',
'key4': 'value4'
};
const value = 'value2';
const key = Object.keys(OBJECT)[Object.values(OBJECT).indexOf(value)];
window.console.log(key); // = key2
The easiest way is to just use Underscore.js:
keys
_.keys(object) Retrieve all the names of the object's properties.
_.keys({one : 1, two : 2, three : 3}); => ["one", "two", "three"]
Yes, you need an extra library, but it's so easy!
best way to get key/value of object.
let obj = {_x000D_
'key1': 'value1',_x000D_
'key2': 'value2',_x000D_
'key3': 'value3',_x000D_
'key4': 'value4'_x000D_
}_x000D_
Object.keys(obj).map(function(k){ _x000D_
console.log("key with value: "+k +" = "+obj[k]) _x000D_
_x000D_
})_x000D_
_x000D_
Well $.each
is a library construct, whereas for ... in
is native js, which should be better
I don't see anything else than for (var key in foo)
.
You can use Object.keys functionality to get the keys like:
const tempObjects={foo:"bar"}
Object.keys(tempObjects).forEach(obj=>{
console.log("Key->"+obj+ "value->"+tempObjects[obj]);
});
Source: Stackoverflow.com