通过正则表达式匹配拆分字符串

Question

I have this following problem. i try to split a string up depending on a regex. I want to to split it by {{ name }} , {{ age }} and so on.

The expected output should look like this:

["hy my name is: ", "{{ name }}", " and i am ", "{{ age }}", " old"]

My current attempt was this here:

 let str = "hy my name is: {{ name }} and i am {{ age }} old"; let vars = str.split(/({{)(.*)(}})/); console.log(vars);

Whats the correct regex for this task?

Answer 1

You need to

• Remove the capturing groups you have and add capturing parentheses around the whole pattern. You need to split with your search pattern, so it will be added to the resulting array after split if it is captured : " If separator is a regular expression that contains capturing parentheses (), matched results are included in the array. "
• Use a lazy . , .*? , instead of the greedy .* . Otherwise, the {{.*}} will match {{ , then any 0 or more chars other than line break chars as many as possible, and then }} , so all {{...}} substrings in between {{ and }} will be put into one match.

JS fixed demo:

 let str = "hy my name is: {{ name }} and i am {{ age }} old"; let vars = str.split(/({{.*?}})/); console.log(vars); // => [ "hy my name is: ", "{{ name }}", " and i am ", "{{ age }}", " old"]

Note that { and } are only special if there is a number inside, like {6} . In {{.*?}} , the curly braces cannot be parsed as limiting quantifiers since there is no number, hence, you may escape { chars in order to prevent any ambiguity.

Also, in case you have a match at the start of the string, you will have an empty element in the resulting array, then you need to remove the empty elements:

str.split(/({{.*?}})/).filter(Boolean)

Answer 2

Instead of split , you may use this regex with match :

/{{.*?}}|.+?(?={{|$)/g

Code:

 let str = "hy my name is: {{ name }} and i am {{ age }} old"; let vars = str.match(/{{.*?}}|.+?(?={{|$)/g); console.log(vars);

RegEx Details:

• {{.*?}} : Match a string within {{...}}
• | : OR
• .+? : Match 1+ of any character that satisfies next lookahead condition
• (?={{|$) : Positive lookahead condition that makes sure that we have wither {{ or end of line at next position