I'm looking for a way to remove the 4th space in a string with a regular expression in javascript.

Example: "Wed Sep 19 2012 08:05:07 GMT-0700 (PDT)" into "Wed Sep 19 2012"

I'm looking for a way to remove the 4th space in a string with a regular expression in javascript.

Example: "Wed Sep 19 2012 08:05:07 GMT-0700 (PDT)" into "Wed Sep 19 2012"

• javascript
• regex

Share Improve this question Follow asked Sep 23, 2012 at 23:41 user1693131user1693131 3111 silver badge44 bronze badges 1

• You can't remove them because strings are immutable, but you can make a new sub-string of the original. – I Hate Lazy Commented Sep 23, 2012 at 23:58

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5 Answers 5

Sorted by: Reset to default 15

var s = "Wed Sep 19 2012 08:05:07 GMT-0700 (PDT)";
s.split(' ').slice(0, 4).join(' ');

Step-by-step:

> s.split(' ')
["Wed", "Sep", "19", "2012", "08:05:07", "GMT-0700", "(PDT)"]
> s.split(' ').slice(0, 4)
["Wed", "Sep", "19", "2012"]
> s.split(' ').slice(0, 4).join(' ')
"Wed Sep 19 2012"

Or removing slice and using the limit parameter of split() instead:

var s = "Wed Sep 19 2012 08:05:07 GMT-0700 (PDT)";
var newValue = s.split(' ', 4).join(' ');

Do you really need regexp for this? This is a very standardised date string... 3-character weekday, 3-character month, 2-character day, 4-character year... The only question is whether the day number is padded with zero.

str.substring(0,15);

If the day number is not padded, then you take 14 characters if the 15th character is a space. Otherwise the above will be fine.

The following removes the fourth space, (and everything following it) from a string:

text = text.replace(/^((?:[^ ]* ){3}[^ ]*) [\S\s]*/, "$1");

While regular expressions aren't the best for this, you can do this:

var string = "Wed Sep 19 2012 08:05:07 GMT-0700 (PDT)";
var regex = /^((\S+\s*?){4})(\s+.*)$/;
var stripped = string.replace(regex, "$1");

which is matching 4 cases of non-space followed by a space then anything to the end of the line. The replace uses the first match and ignores the rest.

The \s inside the first group is matched lazily so ending spaces are automatically stripped. Unfortunately this makes the regex slower, but it won't be appreciable on typical inputs.

However, if you are infact trying to parse ISO standard date strings, then paddy is right and you should just cut off the end. You can also do as Joao suggests and do much more normal processing.

Remember, a regex is probably not what you want most of the time. They are actually fairly crude tools...

I feel it would be better if we search for a pattern using Regular Expression and truncate the string from that point.

var str = "Wed Sep 19 2012 08:05:07 GMT-0700 (PDT)";
var regEx = new RegExp("\\s\\d+\\:"); // pattern match for ' dd:'
var truncatedStr = str.substring(0, str.search(regEx));

We know we do not want the string from just before the time. Therefore, we would create a regular expression to match the time pattern of ' dd:'. Now if we use str.search(regEx), it will return the starting index of the pattern. Which in this case would be 15. Hence taking a substring from 0 to 15 on the main string would return the required result of "Wed Sep 19 2012".