javascript - Format and replace a string with a regular expression -
i have number that's @ least 7 digits long. typical examples: 0000123
, 00001234
, 000012345
i want transform them become respectively: 01:23
, 12:34
, 23:45
which mean replacing whole string last 4 characters , putting colon in middle.
i can last 4 digits (\d{4})$
, can 2 groups this: (\d{2})(\d{2})$
with last option, on string 0000123
$1:$2 match gives me 00001:23
want 01:23
i replace string so:
newval = val.replace(/regex/, '$1:$2');
you need match beginning digits \d*
(or .*
if there can anything):
var val = "0001235"; var newval = val.replace(/^\d*(\d{2})(\d{2})$/, '$1:$2'); console.log(newval);
pattern details:
^
- start of string\d*
- 0+ digits (or.*
match 0+ chars other line break chars)(\d{2})
- group 1 capturing 2 digits(\d{2})
- group 2 capturing 2 digits$
- end of string.
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