Check if string contains substring matching regex

Question

I'm writing a script to check if there's occurence of amex credit card number inside a string.

My code looks like this:

let amexRegex= /^3[47][0-9]{13}$/;

if(text.search(amexRegex) != -1){
    console.log('Found!');
} else {
    console.log('Not found!');
}

When I set textto '378734493671000' (a valid amex credit card number), script prints out Found!, but if I keep that same text and add some text arround it, like this: '378734493671000 ABCDEFG', it prints out Not found!.

What should I change in order to find occurence of substring matching the regex? I don't need a index of substring matching the regex, just true\false.

xs0 · Accepted Answer · 2017-11-18 12:08:43Z

2

The ^ and $ restrict matching to beginning and end of string, respectively. It's probably enough to remove those.

answered Nov 18, 2017 at 12:08

xs0

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Comments

guido · Accepted Answer · 2017-11-18 12:08:56Z

2

You just need to remove ^ and $ which respectively match stat and end of line:

let amexRegex= /3[47][0-9]{13}/;

answered Nov 18, 2017 at 12:08

guido

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Comments

PJProudhon · Accepted Answer · 2017-11-18 12:49:20Z

1

Pay attention that only removing ^ and $ can lead to incorrect matches, such as longer numeric strings. You better replace them by word boundaries:

\b3[47][0-9]{13}\b

Demo

answered Nov 18, 2017 at 12:49

PJProudhon

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Comments

user6748331 · Accepted Answer · 2017-11-18 12:17:18Z

1

let amexRegex = /3[47][0-9]{13}/

if(amenxRegex.test(text) {
  console.log('Found!')
} else {
  console.log('Not found!')
}

answered Nov 18, 2017 at 12:17

user6748331

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