Question

How to get the first digit after the decimal point of a float number in JavaScript

Answer 1

function firstDecimalDigit(f) {
    const s = f.toString();
    const pos = s.indexOf('.');
  
    return s[pos + 1];
}

const f = 231.687612;

console.log(firstDecimalDigit(f));  // "6"



/*
run:

6

*/

 

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Answer 2

function firstDecimalDigit(f) {
    return f.toString().split('.')[1][0];
}

const f = 231.687612;

console.log(firstDecimalDigit(f));   // "6"



/*
run:

6

*/

 

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Answer 3

function firstDecimalDigit(f) {
    return (Math.floor(Math.abs(f) * 10)) % 10;
}

const f = 231.687612;

console.log(firstDecimalDigit(f));   // 6



/*
run:

6

*/

 

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