Comma Operator Returns LAST Value Only?!
⚠️ THIS IS INSANE! The comma operator evaluates ALL expressions but returns ONLY the last one! (1,2,3,4,5) = 5! Used in for loops everywhere but nobody notices. Tag a dev who needs this!
#javascript #javascripttricks #codingchallenge #commaoperator #javascriptoperators #javascriptquiz #javascriptweird #javascriptwtf #forloops #codinginterview #javascriptshorts
with() Changes Variable Scope?!
💥 DEPRECATED BUT STILL WORKS! The 'with' statement changes your scope and makes variables magically refer to object properties! Banned in strict mode but still in old codebases. This caused HUGE security bugs!
#javascript #javascripttricks #codingchallenge #withstatement #scope #javascriptquiz #javascriptweird #javascriptwtf #deprecated #javascriptbugs #javascriptshorts
Object Keys Get AUTO-SORTED?!
Object key order is NOT guaranteed! Numeric string keys get SORTED before other keys. You add 'b' first but '1' appears first in Object.keys()! This auto-sorting will DESTROY your expected order!
#javascript #javascripttricks #object.keys #keyordering #numerickeys #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #objectquirks #advancedjavascript
Labels Let You BREAK NESTED Loops?!
🔥 SECRET FEATURE! You can break out of nested loops using labels! outer: for... break outer; This skips BOTH loops at once! Senior devs don't even know this. Save this for your next interview!
#javascript #javascripttricks #codingchallenge #labeledstatements #breakstatement #nestedloops #javascriptquiz #javascriptweird #codinginterview #codingtips #javascriptshorts
new Function() Ignores Local Scope?!
Function constructor is DANGEROUS! It always runs in GLOBAL scope, ignoring any variables in the enclosing function. Your local 'x' becomes invisible. This scoping behavior will cause HIDDEN bugs!
#javascript #javascripttricks #functionconstructor #globalscope #variablescope #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #scopequirks #advancedjavascript
Tagged Template Does MATH in Strings?!
Tagged templates can EXECUTE CODE! The tag function receives values and can transform them. This one DOUBLES every number. String interpolation becomes code execution!
#javascript #javascripttricks #taggedtemplates #templateliterals #stringinterpolation #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #templateprocessing #advancedjavascript
typeof Never Throws Error?!
typeof is INDESTRUCTIBLE! It works on undeclared variables WITHOUT throwing ReferenceError. Both declared undefined AND never-declared return 'undefined'. You can't tell them apart! This is INSANE!
#javascript #javascripttricks #typeof #undeclaredvariables #referenceerror #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #typechecking #advancedjavascript
Spread Operator Works on STRINGS?!
Spread operator is MAGIC! It works on strings (splits to chars) but NOT on objects. This inconsistency will cause bugs when you least expect it!
#javascript #javascripttricks #spreadoperator #stringiteration #objectiteration #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #iterableprotocol #advancedjavascript
Nullish Coalescing vs Logical OR?!
?? and || are DIFFERENT! Nullish coalescing only checks null/undefined. Logical OR checks ALL falsy values. 0 and '' behave differently! This matters!
#javascript #javascripttricks #nullishcoalescing #logicalor #falsyvalues #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #operatordifferences #advancedjavascript
Labels Can Break ANY Block?!
JavaScript has GOTO in disguise! Labels with break can exit ANY block, not just loops! This code jumps OUT of nested blocks instantly. Most developers have NEVER seen this syntax!
#javascript #javascripttricks #labels #breakstatement #controlflow #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #hiddenfeatures #advancedjavascript
Array Methods Work on NON-Arrays?!
Array methods are DECEPTIVE! They work on any object with length property. This object isn't an array, but map() works on it! JavaScript lies about types!
#javascript #javascripttricks #arraymethods #arraylikeobjects #typecoercion #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #ducktyping #advancedjavascript
String Primitives Have Methods But No Properties?!
Strings are DECEPTIVE! They have methods (auto-boxing) but you can't assign properties. Properties disappear immediately. This is primitive vs object confusion!
#javascript #javascripttricks #stringprimitives #autoboxing #propertyassignment #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #primitivetypes #advancedjavascript
Array Holes Are NOT undefined?!
MIND BLOWN! An empty slot in an array is NOT the same as undefined. The hole doesn't exist as a property! map() SKIPS holes but processes undefined. This invisible difference will break your code!
#javascript #javascripttricks #arrayholes #sparsearrays #undefined #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #arraymethods #advancedjavascript
Array.fill() Shares Same Reference?!
This is a TRAP! Array.fill() with an object puts the SAME object in every slot. Change one, change ALL! Every element points to the same memory location. This silent mutation will destroy your data!
#javascript #javascripttricks #array.fill #objectreference #mutationbugs #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #referencetypes #advancedjavascript
Object Keys Get REORDERED Automatically?!
🚨 THIS IS INSANE! JavaScript silently reorders your object keys! Numbers get sorted, but '01' vs '1' behave differently. Your API response order might be LYING to you! This causes real security bugs!
#javascript #javascripttricks #codingchallenge #javascriptobjects #objectkeys #javascriptquiz #javascriptweird #javascriptwtf #javascriptbugs #codinginterview #json #javascriptshorts
void Operator ERASES Any Value?!
The void operator is JavaScript's BLACK HOLE! It takes ANY expression and returns undefined. Even when the function returns 42, void turns it into NOTHING! This ancient operator will confuse everyone!
#javascript #javascripttricks #voidoperator #undefined #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #operatorquirks #javascriptbugs #advancedjavascript
RegExp lastIndex Mutates Global Matches?!
Global regex has MEMORY! The lastIndex property remembers where it stopped. Reset it to 0 and the same regex matches DIFFERENTLY. This mutation behavior will cause bugs you'll never find!
#javascript #javascripttricks #regexp #lastindex #globalregex #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #regexmutation #advancedjavascript
finally{} OVERRIDES return Statement?!
💥 WATCH THIS NOW! finally block KILLS your return statement! try returns 'A', but finally returns 'B' - guess which one wins? This silent behavior has caused millions in production bugs! Share this NOW!
#javascript #javascripttricks #codingchallenge #trycatchfinally #returnstatement #javascriptquiz #javascriptweird #javascriptwtf #javascriptbugs #codinginterview #errorhandling #javascriptshorts
WeakMap REJECTS Primitive Keys?!
WeakMap has a SECRET rule! It ONLY accepts objects as keys. Try to use a string and it FAILS silently. This hidden restriction will cause bugs you'll never find!
#javascript #javascripttricks #weakmap #objectkeys #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #weakreferences #javascriptbugs #advancedjavascript
Tagged Template Literals Have RAW Property?!
Template literals have a SECRET! The raw property shows escape sequences as LITERAL characters. \n becomes TWO characters, not one newline. This hidden feature will blow your mind!
#javascript #javascripttricks #templateliterals #taggedtemplates #rawproperty #javascriptweird #javascriptquiz #codingchallenge #javascriptshorts #javascriptwtf #stringescaping #advancedjavascript
