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This article mainly introduces jquery how to judge whether there is a number of related knowledge, content detailed and easy to understand, simple and fast operation, with a certain reference value, I believe that everyone will read this jquery how to judge whether there are digital articles will be harvested, let's take a look at it.

In jquery, we can use the following methods to determine whether a variable is a number:

1、$.isNumeric();

jQuery is a built-in function used to determine whether it is a number. If $.isNumeric() is used to determine whether it is a number, some special characters will be treated as octal or decimal numbers, and it will be determined to be true, such as:(Related courses recommended: jQuery tutorial)$.isNumeric(0xFF); //true

$.isNumeric("0xFF"); //true$.isNumeric(3.13); //true

$.isNumeric("3.13"); //true

$.isNumeric(-3.13); //true

$.isNumeric("-3.13"); //true

$.isNumeric("03.13"); //true

$.isNumeric(01); //true

$.isNumeric(001); //true

$.isNumeric(+3.13); //true

$.isNumeric(0xFF); //true

$.isNumeric("0xFF"); //true

$.isNumeric(true); //false

$.isNumeric(NaN); //false

2、isNaN();

js is a function used to determine whether it is a number, it means "not a number", that is,"determine whether it is not a number, if it is not a number, it is true, if it is a number, it is false", its disadvantage is that some variables with empty values, such as null, spaces, etc., will turn them into "0" as a number to deal with: var val=$("#test").val();

var ival=parseInt(val);//if val is a number of character type convert to int if not ival is NaN

alert(typeof(ival));

if(! isNaN(ival)){

alert(val +"is a number");

} else{

alert(val +"not a number");

}

Description: isNaN() function returns false if the passed parameter is a number, otherwise returns true

3. Use regular expressions to judge

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

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

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

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

"^-?\\ d+$" //integer

"^\\d+(" //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

"^((-\\d+(" //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+)(" //floating point number

Example: var r=/^\+? [1-9][0-9]*$/; //Determine whether it is a positive integer

r.test(str);

Or: function isNumber(value) { //Verify whether it is a number

var patrn=/^(-)?\ d+(\.\ d+)?$/;

if (patrn.exec(value)==null || value=="") {

return false

} else {

return true

}

}

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