converting array to regex, not working in match function

Question

I have a lengthy array of location names. I am trying to build a command which, when a phrase is typed into a text box, I can parse the phrase text to determine if any of the locations in my list are mentioned. I have done this successfully with a regex containing a small group of strings which I created manually, but with this array conversion I only get "undefined" as an outcome. My working function (created manually) is shown below, followed by the one I am struggling with. I think this is due to the structure of the RegEx somehow (maybe it needs brackets?) but I can work out how to find the issue. Any help in troubleshooting would be greatly appreciated

working code with manually created regex strings. Note, "readCommandText" is a function I created to read the text to be checked

let colorSet = /\b(red|green|blue)\b/; 

function matchRobot() {
    let text = readCommandText(true);
    let result = text.match(colorSet);
    console.log(`color: ${result[1]}`)
 }

Non working code with array conversion (actual list of locations is much longer). No matter what location I input I still see "undefined"

What am I overlooking?

locationArr = [brisbane, paris, london, singapore, dubai, seattle];
let locations = new RegExp(locationArr.join("|"), "gi");

function matchLoc() {
    let text = readCommandText(true);
    let result = text.match(locations);
    console.log(`location: ${result[1]}`)
 }

I think you should look at your variable names, you are joining the array landmarkArr which i don't see. Then inside the match method you use a variable called landmarks which is also no where to be found. — StackByMe
– StackByMe, Commented Sep 29, 2020 at 10:07
Did you mean to write locationArr = ["brisbane", "paris", "london", "singapore", "dubai", "seattle"]; and then let locations = new RegExp("\\b(" + locationArr.join("|") + ")\\b", "gi");? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Sep 29, 2020 at 10:08
There is so much wrong with it, that I really recommend you to get an editor like Visual Studio Code, which tells you about some common mistakes, like using variables that dont exist — MauriceNino
– MauriceNino, Commented Sep 29, 2020 at 10:15
Thanks @WiktorStribiżew - it was just a typo when writing my question, the code itself has the correct variables, appreciate you checking rather than assuming :) I have edited to correct the typo and Mara below has answered with your comment. Thanks again — sophg
– sophg, Commented Sep 29, 2020 at 23:55

Mara Black · Accepted Answer · 2020-09-29 10:22:08Z

0

You can take a look at this, I used a phrase to mock the text from readCommandText(true); As Wiktor suggested, you can compose your regex like this:

new RegExp("\\b(" + locationArr.join("|") + ")\\b", "gi");

const locationArr = ["brisbane", "paris", "london", "singapore", "dubai", "seattle"];
let locationsRegXp = new RegExp("\\b(" + locationArr.join("|") + ")\\b", "gi");
console.log(locationsRegXp)

function matchLoc() {
  let text = "I wanted to travel to seattle and london this year but 2020.."
  let result = text.match(locationsRegXp);
  console.log("location: " + result)
}

matchLoc();

answered Sep 29, 2020 at 10:22

Mara Black

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1 Comment

sophg Over a year ago

Thanks Mara! I have no idea why this got downvoted, this was exactly what I was missing - how to add the boundary - really appreciate it :)

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