Common Coding Mistakes to Avoid
Even experienced programmers make mistakes.
Undefined variables:
Ensure all variables are declared and initialized before use.
Type coercion:
Be mindful of JavaScript's automatic type conversion, which can lead to unexpected results.
Incorrect scope:
Understand the difference between global and local scope to avoid unintended variable access.
Logical errors:
Carefully review your code for logical inconsistencies that might lead to incorrect output.
Off-by-one errors:
Pay attention to array indices and loop conditions to prevent errors in indexing and iteration.
Infinite loops:
Avoid creating loops that never terminate due to incorrect conditions or missing exit points.
Example:
// Undefined variable error
let result = x + 5; // Assuming x is not declared
// Type coercion error
let age = "30";
let isAdult = age >= 18; // Age will be converted to a number
By being aware of these common pitfalls, you can write more robust and error-free code.
Do you have any specific coding mistakes you've encountered recently?
Even experienced programmers make mistakes.
Undefined variables:
Ensure all variables are declared and initialized before use.
Type coercion:
Be mindful of JavaScript's automatic type conversion, which can lead to unexpected results.
Incorrect scope:
Understand the difference between global and local scope to avoid unintended variable access.
Logical errors:
Carefully review your code for logical inconsistencies that might lead to incorrect output.
Off-by-one errors:
Pay attention to array indices and loop conditions to prevent errors in indexing and iteration.
Infinite loops:
Avoid creating loops that never terminate due to incorrect conditions or missing exit points.
Example:
// Undefined variable error
let result = x + 5; // Assuming x is not declared
// Type coercion error
let age = "30";
let isAdult = age >= 18; // Age will be converted to a number
By being aware of these common pitfalls, you can write more robust and error-free code.
Do you have any specific coding mistakes you've encountered recently?
Let's analyze the Python code step by step:
Moon and Sun
✅ Correct answer: A. Moon and Sun
python
a = "Sun"
b = "Moon"
c = a
a = b
b = c
print(a + " and " + b)
Step-by-step breakdown:
1. `a = "Sun"` → variable `a` now holds `"Sun"`.
2. `b = "Moon"` → variable `b` now holds `"Moon"`.
3. `c = a` → variable `c` is assigned the value of `a`, which is `"Sun"`.
4. `a = b` → variable `a` is now assigned the value of `b`, which is `"Moon"`.
5. `b = c` → variable `b` is now assigned the value of `c`, which is `"Sun"`.
Final values:
-a = "Moon"
-b = "Sun"`
So, the `print(a + " and " + b)` will output:
Moon and Sun
✅ Correct answer: A. Moon and Sun
❤2
a = "10" → Variable a is assigned the string "10".
b = a → Variable b also holds the string "10" (but it's not used afterward).
a = a * 2 → Since a is a string, multiplying it by an integer results in string repetition.
"10" * 2 results in "1010"
print(a) → prints the new value of a, which is "1010".
✅ Correct answer: D. 1010
Let’s analyze the Python code snippet from the image:
✅ Correct answer: C. 7
python
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Edit
def add_n(a, b):
return (a + b)
a = 5
b = 5
print(add_n(4, 3))
Step-by-step explanation:
A function add_n(a, b) is defined to return the sum of a and b.
The variables a = 5 and b = 5 are declared but not used inside the function call — they are irrelevant in this context.
The function is called with explicit arguments: add_n(4, 3), so:
python
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return 4 + 3 # = 7
✅ Correct answer: C. 7
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