JS Identifier Check (ASCII)
JavaScript
Hard
5 views
Problem Description
One string is given. Print YES if it is a valid JavaScript identifier using only ASCII rules: first char is letter/_/$, next chars are letters/digits/_/$. Otherwise NO.
Input Format
One line string.
Constraints
Length up to 2e5.
Official Solution
const fs=require('fs');const s=fs.readFileSync(0,'utf8').trim();if(!s){process.stdout.write('NO');process.exit(0);}const first=s[0];const isLetter=c=>{const x=c.charCodeAt(0);return (x>=65&&x<=90)||(x>=97&&x<=122);};const isDigit=c=>{const x=c.charCodeAt(0);return x>=48&&x<=57;};const okFirst=isLetter(first)||first==='_'||first==='$';if(!okFirst){process.stdout.write('NO');process.exit(0);}for(let i=1;i<s.length;i++){const c=s[i];if(isLetter(c)||isDigit(c)||c==='_'||c==='$')continue;process.stdout.write('NO');process.exit(0);}process.stdout.write('YES');
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