I need to split a string. I have a regex able to match each substring entirely.
I tried using it with String.prototype.matchAll() and it's able to split , but that function accepts "invalid tokens" too: pieces of the string that don't match my regex. For instance:
var re = /\s*(\w+|"[^"]*")\s*/g // matches a word or a quoted string
var str = 'hey ??? "a"b' // the '???' part is not a valid token
var match = str.matchAll(re)
for(var m of match){
console.log("Matched:", m[1])
}Gives me the token hey, "a" and b. Those are indeed the substrings that match my regex, but I would have wanted to get an error in this case, since string contains ??? which is not a valid substring.
How can I do this?
The /\s*(\w+|"[^"]*")\s*/g regex is used to extract multiple pattern matches from a string, it is not meant to validate a string.
If you need to return true or false, you need a regex for validation that has the following properties:
g flag (if used with RegExp#test, it may cause unwelcome side effects and adds confusion (see Why does a RegExp with global flag give wrong results?)).So, in your case, use the two-step approach:
/^\s*(?:(?:\w+|"[^"]*")\s*)*$/.test(text) first and thenconst matches = text.match(/\w+|"[^"]*"/g).See the JavaScript demo:
var extraction_re = /\w+|"[^"]*"/g;
var validation_re = /^\s*(?:(?:\w+|"[^"]*")\s*)*$/;
for (var text of ['hey "a"b', 'hey ??? "a"b']) {
if (validation_re.test(text)) {
console.log("Matched:", text.match(extraction_re))
} else {
console.log(text, "=> No Match!")
}
}