JavaScript Daily jumping Pit Series (ii)

1. Number () converts part of a non-numeric type to 0

Cast to a numeric type function:

Parsefloat, parseint

Pros: Return nan to non-numeric types uniformly

Disadvantage: A part of a string that conforms to a numeric type is also recognized as a numeric value

Parsefloat ("1")//1

parsefloat ("1s")//1, not desired parsefloat (null)//nanparsefloat (undefined)//Nanparsefloat ("") //NaN        

Number

Advantage: The string must all conform to the numeric type to be converted successfully

Disadvantage: Converting part of a non-numeric type to 0

Number ("1")//1Number ("1s")//Nannumber (null)//0, not desired number (UNDEBUG)//  Nannumber ("")//0, not desired          

where number (NULL) and No. ("") will return 0, not Nan, resulting in various bugs.

A solution that determines whether a numeric type is

Use the $.isnumeric function provided by jquery to judge.

$.isnumeric ("1")//true$.isnumeric ("1s")//false$.isnumeric (null)//False$.isnumeric ( Undefined)//False$.isnumeric ("")//false          

All right, with jquery's $.isnumeric function source code:

function(obj) {    // parsefloat NaNs numeric-cast false positives (null|true|false| "")    /////// return!jquery.isarray (obj) && (obj-parsefloat (obj) + 1) >= 0;}, /c9> 

2, "". The Split (",") function returns an array of length 1

Before talking about this problem, we need to say some special values of the Split function.

A special value case for the split function of a string

1, the parameter does not pass, returned contains the original string object, the length is 1 array.

"". Split ()//[""] "Xxcanghai". Split ()//["Xxcanghai"]   

2. Parameters pass an empty string, returning an array that separates each character of the original string

Wakahara string is empty string returns an empty array

"". Split ("")//[] "Xxcanghai". Split ("")//["X", "X", "C", "a", "N", "G", "H", "a", "I"]   

3, the original string is an empty string, the argument is not empty, will return an array containing an empty string

"". Split (",")//[""], error, [] "". Split ("Xxcanghai")//["], error, should be []   

Visible, the original string length is 0, and the delimiter length is greater than 0 o'clock, which returns an array containing an empty string.

Because of this problem, a variety of bugs have been caused.

JavaScript Daily jumping Pit Series (ii)