Nothing to repeat with regexp in Javascript [duplicate]

Question

I'm trying to replace all occurences of {0}, {1}, {2}, etc in a string with Javascript.

Example string:

var str = "Hello, my name is {0} and I'm {1} years.";

I'm tried the following to construct the regexp:

var regex1 = new RegExp("{" + i + "}", "g") var regex2 = new RegExp("\{" + i + "\}", "g")

Both attempts throws the error:

Invalid regular expression: /{0}/: Nothing to repeat

I use replace like this:

str.replace(regex, "Inserted string");

Found all kinds of StackOverflow posts with different solutions, but not quite to solve my case.

This a duplicate of duplicate(s+), e.g. stackoverflow.com/questions/29120713/… — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Aug 20, 2015 at 10:04

deceze · Accepted Answer · 2015-08-20 10:01:51Z

The string literal "\{" results in the string "{". If you need a backslash in there, you need to escape it:

"\\{"

This will results in the regex \{..\}, which is the correct regex syntax.

Having said that, your approach is more than weird. Using a regex you should do something like this:

var substitues = ['foo', 'bar']; str = str.replace(/\{(\d+)\}/, function (match, num) { return substitutes[num]; });

In other words, don't dynamically construct a regex for each value; do one regex which matches all values and lets you substitute them as needed.

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