Question 196203 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – regex replace all leading and trailing non-alphanumeric

What is the correct regex for superTrim() to satisfy the description and pass the test:

// removes all leading and trailing whitespace, newlines, escaped whitespace,
//    escaped punctuation, punctuation, special characters, etc
//    - EVERYTHING leading and trailing that is not alphanumeric.
const superTrim = (src: string) => src.replace(/<-- correct regex here --> /gm, "").trim();


if (import.meta.vitest) {
  const { describe, expect, it, test } = await import("vitest");

  test("superTrim", () => {
    expect(superTrim("John Smith")).toBe("John Smith");
    expect(superTrim("Bobby Lee\n \n,  ")).toBe("Bobby Lee");
    expect(superTrim("Sally Maen n,  ")).toBe("Sally Mae");
    expect(superTrim("JCP Dept. Stores\nAttn: Marketingn , 'n '"))
      .toBe("JCP Dept. Stores\nAttn: Marketing");
  });
}

I did find some similar but different enough existing questions that I think a new question is warranted. I could iterate over the string identifying markers to return a slice but this seems to be regex solution.

Tags:

2

Answers


  1. 0

    You can use this regularity to fulfill your requirements：(^[W\n]*)|([W\n]*$)

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  2. 0

    You just need to capture and return the part you want:

    // returns EVERYTHING bounded by the first and last non-escaped, alphanumeric.
const getLean = (src) => src.match(/^(\+[0-9a-zA-Z]|[^0-9a-zA-Z])*(.*?)([^0-9a-zA-Z]|\+[0-9a-zA-Z])*$/)[2];

console.log(getLean("John Smith") === "John Smith")
console.log(getLean("Bobby Lee\n \n,  ") === "Bobby Lee")
console.log(getLean("Sally Maen n,  ") === "Sally Mae")
console.log(getLean(" %*&-->JCP Dept. Stores\nAttn: Marketingn , 'n '") === "JCP Dept. Stores\nAttn: Marketing");
console.log(getLean("nBobby Lee\n \ct,  ") === "Bobby Lee")

    Regex capturing groups:

    1. ^(\+[0-9a-zA-Z]|[^0-9a-zA-Z])*
      At the beginning of the string matches EITHER a literal one or more times followed by a single alphanumeric, OR any single non-alphanumeric, zero or more times as many times as possible (greedy).
    2. (.*?) the piece you seek
      Anything and everything, left in the middle (non-greedy).
    3. ([^0-9a-zA-Z]|\+[0-9a-zA-Z])*$
      Same as 1, but anchored at the end of the string with the |(OR) reversed just for symmetry
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