How to find the position of the first set bit (1-bit) of a number in TypeScript

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// Function to find the position of the first set bit
function findFirstSetBitPosition(num: number): number {
    // Edge case: If the number is 0, there are no set bits
    if (num === 0) {
        return 0; // Return 0 to indicate no set bit
    }

    /*
     * num & -num isolates the lowest set bit.
     * Math.log2(...) gives the zero-based index of that bit.
     */
    return Math.floor(Math.log2(num & -num));
}

const num: number = 4224; // Binary: 0001 0000 1000 0000

// Find and display the position of the first set bit
const position: number = findFirstSetBitPosition(num);

if (position === 0) {
    console.log("The number has no set bits (it's 0).");
} else {
    console.log("The position of the first set bit is: " + position);
}



/* 
run:

"The position of the first set bit is: 7" 

*/

 



answered Sep 4, 2025 by avibootz
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