Trying to use regex to find a sub-string's urls in array of strings

Question

I have an array of strings. I need to grab the URL's value on each string. I have created a function with Regex to accomplish this. It works fine, but there's an edge case I haven't been able to cover. When there is not any URL:'s value, I get the error: Cannot read property '1' of null.

This is my code:

const arrStr = [
  `describe
    url: https://url-goes-here-/1,
         https://url-goes-here-/2,
         https://url-goes-here-/3
  });`
  ,
  `
  before(() => {
    url: https://url-goes-here-/4
  });
  `,
  `
  before(() => {
    url: https://url-goes-here-/5
  });
  `,
  `describe
    // nothing http link here
  });
  `
]

const getXrayUrl = str => str.match(/url:([^;]+)/)[1].trim().split('(')[0]; // cannot read property '1' of null

const allXrayUrls = arrStr.map(item => getXrayUrl(item));

If I removed the string with no URL value from the array, I get this output:

[ 'https://url-goes-here-/1,\n         https://url-goes-here-/2,\n         https://url-goes-here-/3\n  })', 
  'https://url-goes-here-/4\n  })', 
  'https://url-goes-here-/5\n  })' ]

How do I cover this edge case & return another array with all the string in the level?

Because if match doesn't match, it returns null, not an empty array. Attempting to get the 1 property of null throws an error (because null isn't an object). So if match returns null, substitute an empty array, e.g. (str.match(/url:([^;]+)/) || [])[1] so if there's no match, the expression returns undefined rather than throwing an error. — RobG
– RobG, Commented Jan 14, 2021 at 22:25

Ahmed Yousif · Accepted Answer · 2021-01-15 00:50:25Z

1

According to match function documentation, it returns an array of matches, or null if no matches are found.

If you need to handle the case of a missing URL attribute so check match array is null before accessing the capture group as following:

const match = str.match(/url:\s*([^;]+)\n/)
// in case no match retrun empty string
// split the match on , to handle multi URL case
const url = match? match[1].split(",").map(item => item.trim()) : [""];

after that filter match results removing empty values as following:

arrStr.map(getXrayUrl).flat().filter(item => item !== "");

so final solution as following:

const arrStr = [
  `describe
    url: https://url-goes-here-/1,
         https://url-goes-here-/2,
         https://url-goes-here-/3
  });`
  ,
  `
  before(() => {
    url: https://url-goes-here-/4
  });
  `,
  `
  before(() => {
    url: https://url-goes-here-/5
  });
  `,
  `describe
    // nothing http link here
  });
  ` 
]

const getXrayUrl = str => {
    const match = str.match(/url:\s*([^;]+)\n/)
    // in case no match retrun empty string
    // split the match on , to handle multi URL case
    return match? match[1].split(",").map(item => item.trim()) : [""];
}

const allXrayUrls = arrStr.map(getXrayUrl).flat().filter(item => item !== "");

console.log(allXrayUrls)

console output:

["https://url-goes-here-/1", "https://url-goes-here-/2", "https://url-goes-here-/3", "https://url-goes-here-/4", "https://url-goes-here-/5"]

edited Jan 15, 2021 at 0:50

answered Jan 14, 2021 at 23:27

Ahmed Yousif

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4 Comments

Manuel Abascal Over a year ago

Thanks, it worked like a charm bro! Do you know how to make the first three URLs returned as an array as well? ``` [ "url-goes-here-/1", "url-goes-here-/2", "url-goes-here-/3", "url-goes-here-/4", "url-goes-here-/5" ]

Ahmed Yousif Over a year ago

@ManuelAbascal check the updated solution Is it fit what you want?

Manuel Abascal Over a year ago

Yes it is! However, the first item on the array contains three URLs instead of one, how can flatten it?

Ahmed Yousif Over a year ago

I already updated the solution to fix this issue try it

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