How can I remove the last digits of a number (not string) using JavaScript.

Example:

   Input : 2121.1124
   Output : 2121.112

I google it a lot. But everywhere I found remove string. How can I do it?

This is the code for remove last char of a string.

            var str = "stackoverflow";
            str = str.substring(0, str.length - 1);
            console.log(str);

How can I do it for a digit(not string) ?

How can I remove the last digits of a number (not string) using JavaScript.

Example:

   Input : 2121.1124
   Output : 2121.112

I google it a lot. But everywhere I found remove string. How can I do it?

This is the code for remove last char of a string.

            var str = "stackoverflow";
            str = str.substring(0, str.length - 1);
            console.log(str);

How can I do it for a digit(not string) ?

• javascript

• 1 youre sure you dont want to round ? – john Smith Commented May 14, 2014 at 8:36
• convert it to a string than back to a float if you can do it with a string – edi9999 Commented May 14, 2014 at 8:36
• 1 But what wrong with strings? Truncating a string will give you exactly what you want. Why do you need only number operations? – Gino Pane Commented May 14, 2014 at 8:37
• You are dealing with a float, why the heck are you looking for substring? Number.prototype.toFixed() is the right way. See developer.mozilla/en-US/docs/Web/JavaScript/Reference/… – user1659862 Commented May 14, 2014 at 8:43

3 Answers 3

Use number.toFixed(amountOfDecimals); to round, where amountOfDecimals is 3.

Use Math.floor( number * Math.pow(10, amountOfDecimals) ) / Math.pow(10, amountOfDecimals); to avoid rounding. So, for 3 decimal places, that bees Math.floor( 2121.1124 * 1000 ) / 1000;

Not sure which one you need.

Edited to reflect h2ooooooo's suggestion below.

You can display the decimal numbers using toFixed() like the following:

parseFloat(2121.1124).toFixed(3) this will return 2121.112

output= parseInt(input*1000)/1000

How does it work ?

the parseInt(input*1000) will remove all nums after the third after the decimal.