can any one suggest a good math function in javascript to round integer?

Question

i have to round the value from 2.3456789 to 2.345 .

After . there must be three number only remaining should be removed

Answer 1

Use Math.round().

This will round to 3 decimal places.

var result=Math.round(2.3456789*1000)/1000  //returns 2.345  

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In fact, the formula to round any number to x decimal points is:

1) Multiple the original number by 10^x (10 to the power of x).
2) Apply Math.round() to the result.
3) Divide result by 10^x.

Answer 2

Javascript 1.5+ introduced Number.toFixed(n) and Number.toPrecision(n) - pick one depending on what you need.

Number.toFixed() lets you specify the number of digits after the decimal point (padded if necessary).

(2.3456789).toFixed(3) = "2.346"
(3).toFixed(3) = "3.000"

Number.toPrecision() lets you specify the number of significant figures.

(2.3456789).toPrecision(4) = "2.346"