JS trim method

Last Update:2018-12-03 Source: Internet

Author: User

Tags rtrim

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In JavaScript, we need to use TRIM in many places, but JavaScript does not have an independent trim function or method to use. Therefore, we need to write a trim function to achieve our goal.
For example, Method 1:

String. Prototype. Trim = function (){
// Use a regular expression to separate spaces
// Replace it with a null string.
Return this. Replace (/(^/S *) | (/S * $)/g ,"");
}

Method 2:
Function trim (STR ){
For (VAR I = 0; I <Str. Length & Str. charat (I) = ""; I ++ );
For (var j = Str. length; j> 0 & Str. charat (J-1) = ""; j --);
If (I> J) Return "";
Return Str. substring (I, j );
}

S. In Javascript. replace (/(^/S *) | (/S * $)/g, ""); (^/S *) | (/S * $) what does that mean?

First, replace/(^/S *) | (/S * $)/g ""

Then ,/... /G indicates the place where the wildcard is placed. G indicates the global parameter. (^/S *) or (/S * $) will be replaced ""

Regular Expression matching the first and last blank characters: ^/S * |/S * $ can be used to delete the blank characters (including spaces, tabs, and page breaks) at the beginning and end of a line ), very useful expressions

How to Implement trim in Javascript

If you copy the file directly, the space may be faulty. Please check carefully

Function trim (STR)
{
For (VAR I = 0; I <Str. Length & Str. charat (I) = ""; I ++ );
For (var j = Str. length; j> 0 & Str. charat (J-1) = ""; j --);
If (I> J) Return "";
Return Str. substring (I, j );
}

Method 2:
// Add a function named trim
// A method of the prototype object of the string constructor.
String. Prototype. Trim = function ()
{
// Use a regular expression to separate spaces
// Replace it with a null string.
Return this. Replace (/(^/S *) | (/S * $)/g ,"");
}

// A string with spaces
VaR S = "My length ";

// Display the length before trim
Window. Alert (S + "trim length: (" + S. Length + ")");

// Delete leading and trailing Spaces
S = S. Trim ();
// Display the length after trim
Window. Alert (S + "trim length :(" + S. Length + ")");

Method 3:

// Call the VBScript function in JavaScript to construct a javascript trim Function

<P> </P>
<Script language = VBScript>
Function vbtrimstr (temstr)
Vbtrimstr = trim (temstr)
End Function
</SCRIPT>

<Script language = JavaScript>
Function trimstr (temstr ){
Return vbtrimstr (temstr)
}
</SCRIPT>
<Form name = fmtest>
<Input type = text name = txttest>
<Input type = button name = btnok value = OK>
</Form>
<Script language = JavaScript For = btnok event = onclick>
VaR getstr=document.fmtest.txt test. Value
Alert ("*" + getstr + "*")
Getstr = trimstr (getstr)
Alert ("*" + getstr + "*")
</SCRIPT>
</Body>
</Html>

Javascript trim member functions
Use the code below to make trim a method of all strings. These are useful to place in a global Javascript file encoded by all your pages.

String. Prototype. Trim = function () {return this. Replace (/^/S + |/S + $/g ,"");}
String. Prototype. ltrim = function () {return this. Replace (/^/S + /,"");}
String. Prototype. rtrim = function () {return this. Replace (// s + $ /,"");}
// Example of using TRIM, ltrim, and rtrimvar mystring = "Hello my name is ";
Alert ("*" + mystring. Trim () + "*");
Alert ("*" + mystring. ltrim () + "*");
Alert ("*" + mystring. rtrim () + "*");

Javascript trim stand-alone functions
If you prefer not to modify the string prototype, then you can use the stand-alone functions below.

Function trim (stringtotrim) {return stringtotrim. Replace (/^/S + |/S + $/g ,"");}
Function ltrim (stringtotrim) {return stringtotrim. Replace (/^/S + /,"");}
Function rtrim (stringtotrim) {return stringtotrim. Replace (// s + $ /,"");}
// Example of using TRIM, ltrim, and rtrimvar mystring = "Hello my name is ";
Alert ("*" + trim (mystring) + "*");
Alert ("*" + ltrim (mystring) + "*");
Alert ("*" + rtrim (mystring) + "*");

This article from the csdn blog, reproduced please indicate the source: http://blog.csdn.net/welkin8888/archive/2008/12/18/3551413.aspx

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