Deep understanding of substr and substring_javascript techniques in JS

Substr method

Returns a substring of the specified length starting at the specified position.
Stringvar.substr (start [, length])
Parameters
Stringvar
Required option. The string literal or string object to extract the substring.
Start
Required option. The starting position of the desired substring. The index of the first character in the string is 0.
Length
Options available. The number of characters that should be included in the returned substring.
Description
If length is 0 or negative, an empty string is returned. If this argument is not specified, the substring continues to the end of the stringvar.

Example
The following example shows the use of the Substr method.

function Substrdemo () {  
var s, SS;//declaring variable.  
var s = "The rain in Spain falls mainly in the plain.";  
SS = S.substr (12, 5); Gets the substring.  
return (ss);//Back to "Spain". 
}  

Example: <script type= "Text/javascript" > var str = "0123456789";/alert (str.substring (0));//------------"01234567 Str.substring (5))//------------"56789" alert (str.substring);//-----------"" Alert (str.substring 12 )//-----------"" Alert (str.substring ( -5)),//-----------"0123456789" alert (str.substring ( -10));//----------"  
0123456789 "Alert (str.substring ( -12));//----------" 0123456789 "alert (str.substring (0,5));//----------" 01234 " Alert (str.substring (0,10));//---------"0123456789" alert (str.substring (0,12));//---------"0123456789" alert ( Str.substring (2,0))//----------"(Str.substring (2,2));//----------" "Alert (str.substring (2,5));//------ ----"234" alert (2,12);//---------"23456789" alert (str.substring);---------"Alert" ( Str.substring ( -1,5))//---------"01234" alert (str.substring ( -1,-5));//--------"" Alert (STR.SUBSTR (0));//-------- -------"0123456789" Alert (STR.SUBSTR (5));//---------------"56789" aleRT (STR.SUBSTR);//--------------"" alert (str.substr);//--------------"" Alert (Str.substr ( -5));//--------- -----"0123456789" alert (STR.SUBSTR ( -10));//-------------"0123456789" alert (STR.SUBSTR ( -12));//-------------"  
0123456789 "alert (str.substr 0,5);//-------------" 01234 "alert (STR.SUBSTR);------------" 0123456789 " Alert (STR.SUBSTR (0,12));//------------"0123456789" alert (STR.SUBSTR (2,0));//-------------"" Alert Str.substr (2,2 )//-------------"STR.SUBSTR" alert (2,5);//-------------"23456" alert (STR.SUBSTR (2,12));//------------" 23456789 "alert (str.substr 2,-2);//------------" "Alert (Str.substr ( -1,5));//------------" 01234 "alert (str.substr ( -1,-5));  /-----------"" </script>

Substring method

Returns a substring at the specified position in a string object.
Strvariable.substring (start, end)
"String Literal". Substring (start, end)
Parameters
Start
Indicates the starting position of the substring, starting at 0.
End
Indicates the end position of the substring, starting at 0.
Description
The substring method returns a string containing a substring from start to the last (not including end).
The substring method uses the smaller values in both start and end as the starting point for substrings. For example, strvar.substring (0, 3) and strvar.substring (3, 0) will return the same substring.
If start or end is NaN or negative, replace it with 0.
The length of the substring equals the absolute value of the difference between start and end. For example, the length of the substring returned in strvar.substring (0, 3) and strvar.substring (3, 0) is 3.

Example
The following example shows the use of the substring method.

function Substringdemo () {  
var ss;//Declaration variable.  
var s = "The rain in Spain falls mainly in the plain ...";  
SS = S.substring (12, 17); Takes a substring.  
return (ss);//Back substring "Spain". 

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