Js takes the float decimal point and the last two digits (retain two decimal places)

In js, the most common method for getting the decimal point and the two decimal points is the rounding function. I have previously introduced this common function in js, which is useful here, next let's take a look at some methods to sum up the two digits after the float decimal point.

Use Javascript to get the first two digits of the float decimal point. For example, 22.127456 is used to get 22.13. How can this problem be solved?

1. Discard the fractional part and retain the integer part.

ParseInt (5/2)

2. rounded up. If there is a decimal number, add 1 to the integer part.

Math. ceil (5/2)

3. rounding.

Math. round (5/2)

4. Round down

Math. floor (5/2)

Alternative Method

1. the most stupid way

The Code is as follows:
Function get () { Var s = 22.127456 + ""; Var str = s. substring (0, s. indexOf (".") + 3 ); Alert (str ); }

2. The regular expression works well.

The Code is as follows:
<Script type = "text/javascript"> Onload = function (){ Var a = "23.456322 "; Var aNew; Var re =/([0-9] +. [0-9] {2}) [0-9] */; ANew = a. replace (re, "$1 "); Alert (aNew ); } </Script>

3. He is smart .....

The Code is as follows:
<Script> Var num = 22.127456; Alert (Math. round (num * 100)/100 ); </Script>

4. Friends who will use fresh things... but IE5.5 + is required.

 

5. js retains 2 decimal places (mandatory)

If the number of decimal places is greater than 2 digits, the above function is no problem, but if it is less than 2 digits, for example: changeTwoDecimal (3.1), 3.1 is returned, if you must use the format 3.10, you need the following function:

The Code is as follows:
Function changeTwoDecimal_f (x ){ Var f_x = parseFloat (x ); If (isNaN (f_x )){ Alert ('function: changeTwoDecimal-> parameter error '); Return false; } Var f_x = Math. round (x * 100)/100; Var s_x = f_x.toString (); Var pos_decimal = s_x.indexOf ('.'); If (pos_decimal <0 ){ Pos_decimal = s_x.length; S_x + = '.'; } While (s_x.length <= pos_decimal + 2 ){ S_x + = '0 '; } Return s_x; }

Function: rounds a floating point number to the second place after the decimal point. If there are less than two digits, add 0,
This function returns the string format usage: changeTwoDecimal (3.1415926) returns 3.14 changeTwoDecimal (3.1) returns 3.10