What are the list of cases error thrown from non-strict mode to strict mode?
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
When you apply 'use strict'; syntax, some of the below cases will throw a SyntaxError before executing the script
- When you use Octal syntax
var n = 022;
- Using
withstatement - When you use delete operator on a variable name
- Using eval or arguments as variable or function argument name
- When you use newly reserved keywords
- When you declare a function in a block and access it from outside of the block
if (someCondition) {
function f() {}
}
f(); // ReferenceError: f is not defined
Hence, the errors from above cases are helpful to avoid errors in development/production environments.
Candidate Response Strategy & Interview Tips
- Start with a concise one-sentence summary: Deliver a direct, confident answer first before expanding into nuances.
- Demonstrate real-world trade-offs: Discuss where this approach excels and when you would avoid it in production systems.
- Discuss complexity & edge cases: Proactively explain time/space complexity or boundary conditions (null values, scale limits).
- Prepare for interviewer follow-ups: Technical hiring panels frequently probe deeper into concurrency, backward compatibility, or alternative libraries.