I’m trying to extract a substring from a file with JavaScript Regex. Here is a slice from the file :
DATE:20091201T220000
SUMMARY:Dad's birthday
the field I want to extract is “Summary”. Here is the approach:
extractSummary : function(iCalContent) {
/*
input : iCal file content
return : Event summary
*/
var arr = iCalContent.match(/^SUMMARY:(.)*$/g);
return(arr);
}
function extractSummary(iCalContent) {
var rx = /nSUMMARY:(.*)n/g;
var arr = rx.exec(iCalContent);
return arr[1];
}
You need these changes:
-
Put the
*inside the parenthesis as
suggested above. Otherwise your matching
group will contain only one
character. -
Get rid of the
^and$. With the global option they match on start and end of the full string, rather than on start and end of lines. Match on explicit newlines instead. -
I suppose you want the matching group (what’s
inside the parenthesis) rather than
the full array?arr[0]is
the full match ("nSUMMARY:...") and
the next indexes contain the group
matches. -
String.match(regexp) is
supposed to return an array with the
matches. In my browser it doesn’t (Safari on Mac returns only the full
match, not the groups), but
Regexp.exec(string) works.
1
You need to use the m flag:
multiline; treat beginning and end characters (^ and $) as working
over multiple lines (i.e., match the beginning or end of each line
(delimited by n or r), not only the very beginning or end of the
whole input string)
Also put the * in the right place:
"DATE:20091201T220000rnSUMMARY:Dad's birthday".match(/^SUMMARY:(.*)$/gm);
//------------------------------------------------------------------^ ^
//-----------------------------------------------------------------------|
Your regular expression most likely wants to be
/nSUMMARY:(.*)$/g
A helpful little trick I like to use is to default assign on match with an array.
var arr = iCalContent.match(/nSUMMARY:(.*)$/g) || [""]; //could also use null for empty value
return arr[0];
This way you don’t get annoying type errors when you go to use arr
3
(.*) instead of (.)* would be a start. The latter will only capture the last character on the line.
Also, no need to escape the :.
This code works:
let str = "governance[string_i_want]";
let res = str.match(/[^governance[](.*)[^]]/g);
console.log(res);res will equal “string_i_want”. However, in this example res is still an array, so do not treat res like a string.
By grouping the characters I do not want, using [^string], and matching on what is between the brackets, the code extracts the string I want!
You can try it out here: https://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_match_regexp
Good luck.
1
You should use this :
var arr = iCalContent.match(/^SUMMARY:(.)*$/g);
return(arr[0]);
this is how you can parse iCal files with javascript
function calParse(str) {
function parse() {
var obj = {};
while(str.length) {
var p = str.shift().split(":");
var k = p.shift(), p = p.join();
switch(k) {
case "BEGIN":
obj[p] = parse();
break;
case "END":
return obj;
default:
obj[k] = p;
}
}
return obj;
}
str = str.replace(/n /g, " ").split("n");
return parse().VCALENDAR;
}
example =
'BEGIN:VCALENDARn'+
'VERSION:2.0n'+
'PRODID:-//hacksw/handcal//NONSGML v1.0//ENn'+
'BEGIN:VEVENTn'+
'DTSTART:19970714T170000Zn'+
'DTEND:19970715T035959Zn'+
'SUMMARY:Bastille Day Partyn'+
'END:VEVENTn'+
'END:VCALENDARn'
cal = calParse(example);
alert(cal.VEVENT.SUMMARY);