javascript - Truncate float (not rounded) to 2 decimal places - Stack Overflow

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Please, I need convert String into Float or Double in Javascript. But I don't want it round it. I want just fixed 2 decimal places Number which means input 0.996 return me 0.99 and not 1.

// 1. Convert number to float strip to 2 decimal places
var total = ',996' // (or 0.996 if you want, doesn't matter)
total = Math.round(parseFloat(
                   total.replace (',', '.')
)).toFixed(2);

console.log ( typeof total );
console.log ( total );

After this, total is not a number anymore. It's a String with value 1

It's possible to convert string into decimal number with 2 fixed places without rounding?

If you're interested about simple spent manager, I'm programmit it here

Thank you very much for any advice

Best Regards

Please, I need convert String into Float or Double in Javascript. But I don't want it round it. I want just fixed 2 decimal places Number which means input 0.996 return me 0.99 and not 1.

// 1. Convert number to float strip to 2 decimal places
var total = ',996' // (or 0.996 if you want, doesn't matter)
total = Math.round(parseFloat(
                   total.replace (',', '.')
)).toFixed(2);

console.log ( typeof total );
console.log ( total );

After this, total is not a number anymore. It's a String with value 1

It's possible to convert string into decimal number with 2 fixed places without rounding?

If you're interested about simple spent manager, I'm programmit it here https://codepen.io/littleTheRabbit/pen/JjYWjRG

Thank you very much for any advice

Best Regards

• javascript
• floating-point
• rounding

Share Improve this question Follow edited Apr 25, 2020 at 15:55 user2864740 62.1k1515 gold badges158158 silver badges229229 bronze badges asked Apr 25, 2020 at 15:42 Bambi BunnyBambi Bunny 1,43833 gold badges1313 silver badges2121 bronze badges

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 5

This can be done by dropping the extra digits you don't want by using multiplication and division. For example, if you want 0.994 to be 0.99, you can multiply by 100 (to cover 2 decimal places), then truncate the number, and then divide it back by 100 to it to the original decimal place.

example:

  0.994 * 100 = 99.4
  99.4 truncated = 99.0
  99.0 / 100 = 0.99

So here is a function that will do that:

const truncateByDecimalPlace = (value, numDecimalPlaces) =>
  Math.trunc(value * Math.pow(10, numDecimalPlaces)) / Math.pow(10, numDecimalPlaces)

console.log(truncateByDecimalPlace(0.996, 2)) // 0.99

Please, I need convert String into Float or Double in Javascript. But I don't want it round it. I want just fixed 2 decimal places Number which means input 0.996 return me 0.99 and not 1.

// 1. Convert number to float strip to 2 decimal places
var total = ',996' // (or 0.996 if you want, doesn't matter)
total = Math.round(parseFloat(
                   total.replace (',', '.')
)).toFixed(2);

console.log ( typeof total );
console.log ( total );

After this, total is not a number anymore. It's a String with value 1

It's possible to convert string into decimal number with 2 fixed places without rounding?

If you're interested about simple spent manager, I'm programmit it here

Thank you very much for any advice

Best Regards

Please, I need convert String into Float or Double in Javascript. But I don't want it round it. I want just fixed 2 decimal places Number which means input 0.996 return me 0.99 and not 1.

// 1. Convert number to float strip to 2 decimal places
var total = ',996' // (or 0.996 if you want, doesn't matter)
total = Math.round(parseFloat(
                   total.replace (',', '.')
)).toFixed(2);

console.log ( typeof total );
console.log ( total );

After this, total is not a number anymore. It's a String with value 1

It's possible to convert string into decimal number with 2 fixed places without rounding?

If you're interested about simple spent manager, I'm programmit it here https://codepen.io/littleTheRabbit/pen/JjYWjRG

Thank you very much for any advice

Best Regards

• javascript
• floating-point
• rounding

Share Improve this question Follow edited Apr 25, 2020 at 15:55 user2864740 62.1k1515 gold badges158158 silver badges229229 bronze badges asked Apr 25, 2020 at 15:42 Bambi BunnyBambi Bunny 1,43833 gold badges1313 silver badges2121 bronze badges

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 5

This can be done by dropping the extra digits you don't want by using multiplication and division. For example, if you want 0.994 to be 0.99, you can multiply by 100 (to cover 2 decimal places), then truncate the number, and then divide it back by 100 to it to the original decimal place.

example:

  0.994 * 100 = 99.4
  99.4 truncated = 99.0
  99.0 / 100 = 0.99

So here is a function that will do that:

const truncateByDecimalPlace = (value, numDecimalPlaces) =>
  Math.trunc(value * Math.pow(10, numDecimalPlaces)) / Math.pow(10, numDecimalPlaces)

console.log(truncateByDecimalPlace(0.996, 2)) // 0.99

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