const regex = /\b(4[0-9]{3}[ -])([0-9]{4}[ -]){2}[0-9]\b|\b4[0-9][0-9]{11}\b|\b(4[0-9]{3}[ -])([0-9]{4}[ -]){2}(?:[0-9]{4})?$\b|\b4[0-9][0-9]{14}\b|\b(4[0-9]{3}[ -])([0-9]{4}[ -]){3}(?:[0-9]{3})?$\b|\b4[0-9][0-9]{17}\b/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('\\b(4[0-9]{3}[ -])([0-9]{4}[ -]){2}[0-9]\\b|\\b4[0-9][0-9]{11}\\b|\\b(4[0-9]{3}[ -])([0-9]{4}[ -]){2}(?:[0-9]{4})?$\\b|\\b4[0-9][0-9]{14}\\b|\\b(4[0-9]{3}[ -])([0-9]{4}[ -]){3}(?:[0-9]{3})?$\\b|\\b4[0-9][0-9]{17}\\b', 'gm')
const str = `Visa:
Requirements: Visa numbers start with the number 4 and have either 13, 16, or 19 digits (new cards).
Pattern Parts:
Starts with number 4 and 13 length:
1) \\b(4[0-9]{3}[ -])([0-9]{4}[ -]){2}[0-9]\\b|\\b4[0-9][0-9]{11}\\b
Starts with number 4 and 16 length:
2) \\b(4[0-9]{3}[ -])([0-9]{4}[ -]){2}(?:[0-9]{4})?\$\\b|\\b4[0-9][0-9]{14}\\b
Starts with number 4 and 19 length:
3) \\b(4[0-9]{3}[ -])([0-9]{4}[ -]){3}(?:[0-9]{3})?\$\\b|\\b4[0-9][0-9]{17}\\b
Combining 1-3 to form one pattern:
\\b(4[0-9]{3}[ -])([0-9]{4}[ -]){2}[0-9]\\b|\\b4[0-9][0-9]{11}\\b|\\b(4[0-9]{3}[ -])([0-9]{4}[ -]){2}(?:[0-9]{4})?\$\\b|\\b4[0-9][0-9]{14}\\b|\\b(4[0-9]{3}[ -])([0-9]{4}[ -]){3}(?:[0-9]{3})?\$\\b|\\b4[0-9][0-9]{17}\\b
Test Cases:
Should fire:
13 length, no space, start with 4 4123123412341
13 length, dashes, start with 4 4123-1234-1234-1
13 length, spaces, start with 4 4123 1234 1234 1
16 length, no space, start with 4 4221123412341234
16 length, dashes, start with 4 4221-1234-1234-1234
16 length, spaces, start with 4 4221 1234 1234 1234
19 length, no space, start with 4 4241123412341234123
19 length, dashes, start with 4 4241-1234-1234-1234-123
19 length, spaces, start with 4 4241 1234 1234 1234-123
Should not fire:
16 length, no space, not start with 51-55 5623123412341234
16 length, dashes, not start with 51-55 5623-1234-1234-1234
16 length, spaces, not start with 51-55 5623 1234 1234 1234
16 length, no space, not start with 2221-2720 2220123412341234
16 length, dashes, not start with 2221-2720 2220-1234-1234-1234
16 length, spaces, not start with 2221-2720 2220 1234 1234 1234
Non 16 length, matches 51 pattern start 5123-1234-1234-123
Non 16 length, matches 2221 pattern start 2221-1234-1234-123
Malformed, matches 51 pattern start 51-2312-34-1234-1234
`;
// Reset `lastIndex` if this regex is defined globally
// regex.lastIndex = 0;
let m;
while ((m = regex.exec(str)) !== null) {
// This is necessary to avoid infinite loops with zero-width matches
if (m.index === regex.lastIndex) {
regex.lastIndex++;
}
// The result can be accessed through the `m`-variable.
m.forEach((match, groupIndex) => {
console.log(`Found match, group ${groupIndex}: ${match}`);
});
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions