Sometimes you need to increment a value in an object. Read this article to learn how to increment a value in an object using JavaScript and avoid unnecessary bugs in the process. Let’s get started.
How to increment a value in an object using JavaScript
We create a simple JavaScript object of key-value pairs.
Example:
// Create the 'obj' object
const obj = {
key1: undefined,
key2: 2,
};
console.log(obj);Output:
{ key1: undefined, key2: 2 }To increment a value in an object, we first use the '.' or '[]' to access the value of a particular key.
We then increment the value of the key being accessed by 1. However, the output will return NaN when the value of that key is undefined.
Example:
// Create the 'obj' object
const obj = {
key1: undefined,
key2: 2,
};
// Increase the value of key1 and key2 by 1
obj.key1 = obj.key1 + 1;
obj["key2"] = obj["key2"] + 1;
console.log(obj);Output:
{ key1: NaN, key2: 3 }We will use the conditional (ternary) operator '?:' for our program to work around this error. The conditional (ternary) operator is a shortened version of the if-else statement.
Syntax:
condition ? exprIfTrue : exprIfFalse
Parameters:
condition: an expression used as a condition. Evaluates to FALSE if it is one of the values NaN, null, "", 0, and undefined.
exprIfTrue: an expression to be executed if the condition is TRUE.
exprIfFalse: an expression to be executed if the condition is FALSE.
Example:
// Create the 'obj' object
const obj = {
key1: undefined,
key2: 2,
};
// Use the conditional (ternary) operator '?:' to Increment the values in the 'obj' object
obj.key1 ? obj.key1++ : (obj.key1 = 1);
obj.key2 ? obj.key2++ : (obj.key2 = 1);
console.log(obj);Output:
{ key1: 1, key2: 3 }If the value of the key entered as a condition is defined, it will be incremented by 1. If the value of the key entered as a condition is undefined, it will be initialized to 1.
You can also use the or operator '||' to increment a value in the obj object.
Example:
// Create the 'obj' object
const obj = {
key1: undefined,
key2: 2,
};
// Use the or operator '||' to Increment the values in the 'obj' object
obj.key1 = ++obj.key1 || 1;
obj.key2 = ++obj.key2 || 1;
console.log(obj);Output:
{ key1: 1, key2: 3 }Summary
When you increment a value in an object using JavaScript, the program will return NaN if the value is undefined. So you must check if the value is undefined before incrementing a value in an object. Thank you for reading.
Maybe you are interested:
- Get an Object’s Key by its Value using JavaScript
- Set all Values in an Object to Null using JavaScript
- Get an Object’s Value by Index in JavaScript
Hello, my name’s Bruce Warren. You can call me Bruce. I’m interested in programming languages, so I am here to share my knowledge of programming languages with you, especially knowledge of C, C++, Java, JS, PHP.
Name of the university: KMA
Major: ATTT
Programming Languages: C, C++, Java, JS, PHP
