Advanced JavaScript (5) Functions for taking decimals and integers in js

Function to get the integer part of a decimal in js

Discard the decimal part,Keep the integer part

js:parseInt (7/2)

Round up,If there is a decimal, add the integer part1

js: Math.ceil(7/2)

Rounding

js: Math.round(7/2)

Rounding down

js: Math.floor(7/2)

Attachment: How to determine the input numerical type (use without quotes!)

In fact, it is to use regular expressions.

"^\\d+$" // Non-negative integer (positive integer +0)

"^[0-9]* [1-9][0-9]*$"// Positive integer

"^((-\\d+)|(0+))$" // Not positive Integer (negative integer + 0)

"^-[0-9]*[1-9][0-9]*$" // Negative integers                                                                                                         //

Non-negative floating point number (positive floating point number

+0

) "^(([0-9]+\\.[0- 9]*[1-9][0-9]*)|([0-9]*[1-9][0-9]*\\.[0-9]+)|([0-9 ]*[1-9][0-9]*))$" //Positive floating point number                                                               ?)|(0+(\\.0+)?))$"//

Non-positive floating point number (negative floating point number

+0

）      

"^(-(([0-9]+\\.[0-9]*[1-9][0-9]*)|([0-9 ]*[1-9][0-9]*\\.[0-9]+)|([0-9]*[1-9][0-9]*)))$"//Negative floating point number ​ "^(-?\\d+)(\\.\\d+)?$"//

Floating point number

Example

var r = /^[0-9]*[1-9][0-9]*$///Positive integer

r.test(str); //str

is the character you want to judge and the execution result is

true or

false

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