How can I test if a RegEx matches a string exactly?
var r = /a/;
r.test("a"); // returns true
r.test("ba"); // returns true
testExact(r, "ba"); // should return false
testExact(r, "a"); // should return true
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Did you intend to write "var r = /./;"?Prestaul– Prestaul2009-01-15 15:49:49 +00:00Commented Jan 15, 2009 at 15:49
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I intended to write /a/ (: thanks.Serhat Ozgel– Serhat Ozgel2009-01-15 16:17:46 +00:00Commented Jan 15, 2009 at 16:17
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Possible duplicate of Regex - Match whole stringVadzim– Vadzim2016-12-14 16:19:34 +00:00Commented Dec 14, 2016 at 16:19
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6 Answers
Either modify the pattern beforehand so that it only matches the entire string:
var r = /^a$/
or check afterward whether the pattern matched the whole string:
function matchExact(r, str) {
var match = str.match(r);
return match && str === match[0];
}
1 Comment
WhyNotHugo
See svante's answer below as well, since it give an explanation as to why this works.
Write your regex differently:
var r = /^a$/;
r.test('a'); // true
r.test('ba'); // false
Comments
If you do not use any placeholders (as the "exactly" seems to imply), how about string comparison instead?
If you do use placeholders, ^ and $ match the beginning and the end of a string, respectively.
Comments
In case anyone receives an error like
Syntax Error: Invalid regular expression
by using the .match() function. You could always go back to the roots: !!note this code is for matchin an exact string, if you want to search for an exact phrase in a string, you should filter it before hand
console.log("Exact data found: ", hasExactString("?hello", "?hello"))
console.log("Exact data found: ", hasExactString("?hello", "?helloBye"))
function hasExactString(data, searchTerm) {
console.log("search for ", searchTerm, " in ", data);
data = data.toLowerCase(); //if search term should be case insensitive
const searchExpressionLength = searchTerm.length;
const dataInputLength = data.length;
if (dataInputLength != searchExpressionLength) {
return false;
}
else {
//search letter by letter -back to the roots
for (var i = 0; i < searchExpressionLength; i++) {
if (data[i] != searchTerm[i]) {
return false;
}
}
return true;
}
}...13 years late, but nonetheless^^
Comments
var data = {"values": [
{"name":0,"value":0.12791263050161572},
{"name":1,"value":0.13158780927382124}
]};
//JSON to string conversion
var a = JSON.stringify(data);
// replace all name with "x"- global matching
var t = a.replace(/name/g,"x");
// replace exactly the value rather than all values
var d = t.replace(/"value"/g, '"y"');
// String to JSON conversion
var data = JSON.parse(d);
answered May 13, 2014 at 6:57
Aravind Cheekkallur
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1 Comment
ahsan ayub
It can be solved simply by regex expression, this approach is very costly and it may did not go well. depending on input. Please consider using regex.
Here's what is (IMO) by far the best solution in one line, per modern javascript standards:
const str1 = 'abc';
const str2 = 'abc';
return (str1 === str2); // true
const str1 = 'abcd';
const str2 = 'abc';
return (str1 === str2); // false
const str1 = 'abc';
const str2 = 'abcd';
return (str1 === str2); // false
1 Comment
JHH
This is nonsense, it has nothing to do with RegExp. How does this address the question if you e.g. want to test if
str1 exactly matches /[a-z]{3}/?