THIS

@danbaldevs9r0

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Why it worked

The video leverages a surprising and powerful JavaScript trick that feels 'illegal' due to its ability to execute arbitrary code from user input. This element of surprise and the demonstration of a seemingly simple line of code having complex functionality likely drove engagement.

Summary

This video demonstrates a powerful JavaScript hack using `alert(eval(prompt()))`. It shows how a single line of code can take user input, treat it as executable JavaScript, and then display the result, highlighting its 'illegal' feeling power.

Structure

1Introduce the JavaScript hack
2Explain how `prompt` and `eval` work together
3Demonstrate creating a function at runtime
4Show executing simple math
5Conclude on the 'illegal' feeling power of the code

On-screen text

javascript hacks alert(eval(prompt())); THIS THIS ONE LINE OF JAVASCRIPT LITERALLY FEELS ILLEGAL. IT FIRST ASKS THE USER FOR TEXT THEN EVAL TREATS THAT TEXT LIKE REAL JAVASCRIPT CODE, AND FINALLY ALERT SHOWS WHATEVER THE CODE RETURNS. NOW WATCH WHAT THIS DOES. IF THE USER TYPES THIS, function hi(){ return "You're a JS king 👑"; } hi(); JAVASCRIPT WILL ACTUALLY CREATE THIS FUNCTION AT RUNTIME AND INSTANTLY EXECUTE IT. AND IF THE USER TYPES SOMETHING SIMPLE LIKE (50 * 5) / 2 TURNS IT INTO ACTUAL CODE, RUNS THE MATH, AND ALERT SHOWS THE FINAL RESULT. ALL OF THIS FROM A SINGLE LINE OF JAVASCRIPT. THAT'S WHY IT FEELS ILLEGAL.

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Transcript

THIS ONE LINE OF JAVASCRIPT LITERALLY FEELS ILLEGAL. IT FIRST ASKS THE USER FOR TEXT, THEN EVAL TREATS THAT TEXT LIKE REAL JAVASCRIPT CODE, AND FINALLY ALERT SHOWS WHATEVER THE CODE RETURNS. NOW WATCH WHAT THIS DOES. IF THE USER TYPES THIS, function hi(){ return "You're a JS king 👑"; } hi(); JAVASCRIPT WILL ACTUALLY CREATE THIS FUNCTION AT RUNTIME AND INSTANTLY EXECUTE IT. AND IF THE USER TYPES SOMETHING SIMPLE LIKE (50 * 5) / 2 TURNS IT INTO ACTUAL CODE, RUNS THE MATH, AND ALERT SHOWS THE FINAL RESULT. ALL OF THIS FROM A SINGLE LINE OF JAVASCRIPT. THAT'S WHY IT FEELS ILLEGAL.