In JavaScript, you can check if a value exists or not using different methods like if else, switch, ternary operator, etc. Once you have determined that the value does not exist, you can assign a default value to avoid errors while performing any operations on that value.
In ECMAScript 2021, you can use the ?? nullish coalescing operator to assign a default value when the value is nullish (either null or undefined). Here is an example:
let value;
value = value ?? 'default value';
console.log(value); // Output: default value
In the above example, we have defined a variable value that does not have any assigned value. Next, we have used the nullish coalescing operator to assign a default value default value to the value variable if it is nullish. The output will be default value as there was no previously assigned value to the variable.
Another example code:
let value = null;
value = value ?? 'default value';
console.log(value); // Output: default value
This code assigns a default value to value when it is nullish. Using the ?? operator avoids errors when trying to perform operations on nullish values.