What is a rest parameter?
Interviewer Expectations for this Question
01
Core Competency
Assesses fundamental understanding of JavaScript conventions, runtime behavior, and memory/performance considerations.
02
Evaluation Criteria
Hiring managers look for precision, avoidance of ambiguous jargon, and ability to explain trade-offs under real production conditions.
Comprehensive Model Answer
Verified Solution
Rest parameter is an improved way to handle function parameters which allows us to represent an indefinite number of arguments as an array. The syntax would be as below,
function f(a, b, ...theArgs) {
// ...
}
For example, let's take a sum example to calculate on dynamic number of parameters,
function sum(...args) {
let total = 0;
for (const i of args) {
total += i;
}
return total;
}
console.log(sum(1, 2)); //3
console.log(sum(1, 2, 3)); //6
console.log(sum(1, 2, 3, 4)); //10
console.log(sum(1, 2, 3, 4, 5)); //15
Note: Rest parameter is added in ES2015 or ES6
Candidate Response Strategy & Interview Tips
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