Pfthb

x variable has a JSON value like below

let x = ['a': 7, 'b': 8, 'a': 1, 'b': 5 ] 

the output should be

y = [7,1];

How can I get the JSON multiple object first value only? Thanks.

Object properties are only reliably ordered in semi-modern browsers - your desired output may not be reliably determinable from code on running older browsers (unless you have a set order of the property names in an array, or unless the properties are numeric, or something like that). But, on newer browsers, you can .map the input array and extract the first value found by Object.values from the object you're iterating over:

const x = ['a': 7, 'b': 8, 'a': 1, 'b': 5 ];
const result = x.map((obj) => Object.values(obj)[0]);
console.log(result);

Also note that, as always, there's no such thing as a "JSON Object". If you have an object or array, then you have an object or array, full stop. JSON format is a method of representing an object in a string, like const myJSON = '"foo":"bar"'. If there are no strings, serialization, or deserialization involved, then JSON is not involved either.

If you're sure about the key you want to access, then you just need to iterate from x and then push the result on your y.

let x = ['a': 7, 'b': 8, 'a': 1, 'b': 5 ];
let y = ;

for(let i in x) 
 y.push(x[i].a);


console.log(y);

You could combine Array#map with Object.values() to achieve this; the mapping would transform each item of your input array x to the resulting array y. For each item in the resulting array y, you would select the first value of the corresponding item from x.

To select the first value of an item in x, that item is passed to Object.values(). The result of Object.values() is an array of the values of that item, and it's by this that you can access and "map" the first value of each item in y:

let x = ['a': 7, 'b': 8, 'a': 1, 'b': 5 ]

let y = x.map(item => Object.values(item)[0]);

console.log(y)

var data = ;
x.forEach((elem) => 
 data.push(elem.a);
);