在JavaScript中计算小数点后的数字

Question

I have a problem in JavaScript. Is it possible to check how many numbers are after the decimal point? I tried to do it using a.toString().split(".")[1] ), but if there is no decimal point in the number, there is an error. What should I do if I want the system to do nothing if there is no decimal point?

Answer 1

You're on the right track. You can also .includes('.') to test if it contains a decimal along with .length to return the length of the decimal portion.

 function decimalCount (number) { // Convert to String const numberAsString = number.toString(); // String Contains Decimal if (numberAsString.includes('.')) { return numberAsString.split('.')[1].length; } // String Does Not Contain Decimal return 0; } console.log(decimalCount(1.123456789)) // 9 console.log(decimalCount(123456789)) // 0 

Answer 2

Convert to a string, split on “.”, then when there is no “.” to split on, assume it's empty string '' (the part you're missing), then get said string's length:

 function numDigitsAfterDecimal(x) { var afterDecimalStr = x.toString().split('.')[1] || '' return afterDecimalStr.length } console.log(numDigitsAfterDecimal(1.23456)) console.log(numDigitsAfterDecimal(0)) 

Answer 3

You could check if no dot is available, then return zero, otherwise return the delta of the lenght and index with an adjustment.

 function getDigits(v) { var s = v.toString(), i = s.indexOf('.') + 1; return i && s.length - i; } console.log(getDigits(0)); console.log(getDigits(0.002)); console.log(getDigits(7.654321)); console.log(getDigits(1234567890.654321)); 

Answer 4

The condition you need is:

number.split('.')[1].length

It checks if there are any numbers after the dot which separates the number from its decimal part.

I'm not sure if you are able to use split on numbers though. If not, parse it to a string.

Answer 5

You first need to convert the decimal number to string and then get the count of character after decimal point,

var a = 10.4578;
var str = a.toString();
if(str){
   var val = str.split('.');
   if(val && val.length == 2){
     alert('Length of number after decimal point is ', val[1].length);
   } else {
    alert('Not a decimal number');
   }
}

The output is 4