string-remove-duplicate-heads-tails^6.0.1

Detect and (recursively) remove head and tail wrappings around the input string

Install via npm

npm i string-remove-duplicate-heads-tails

This package is ESM only: Node 12+ is needed to use it and it must be imported instead of required:

import { remDup } from "string-remove-duplicate-heads-tails";

If you need a legacy version which works with require, use version 5.1.0:

"string-remove-duplicate-heads-tails": "5.1.0",

Install as a script, via CDN

Put this in your HTML:

<script src="https://cdn.jsdelivr.net/npm/string-remove-duplicate-heads-tails/dist/string-remove-duplicate-heads-tails.umd.js"></script>

Then, you’ll get a global variable stringRemoveDuplicateHeadsTails in your Global object and you consume it like this:

const { remDup } = stringRemoveDuplicateHeadsTails;

Trivia

This program has 63 assertions in its unit tests. That's more than all unit test assertions' median (48) but less than geometric mean (70).

In monorepo, one other package, json-variables, consumes this package.

Quick Take

import { strict as assert } from "assert";
import { remDup } from "string-remove-duplicate-heads-tails";

assert.equal(
  remDup("{{ Hi {{ first_name }}! }}", {
    heads: "{{ ",
    tails: " }}",
  }),
  "Hi {{ first_name }}!"
);

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The Purpose

Let's say, you know that variables are wrapped with heads, for example, {{ and tails, }}.

For example:

"Hi {{ first_name }}!"

This library detects and deletes redundant heads and tails wrapped around the whole input string:

"{{ Hi {{ first_name }}! }}" => "Hi {{ first_name }}!"

But it's also smart and detects legit heads and tails at the edges of string:

:exclamation: {{ first_name }} {{ last_name }} is not turned into first_name }} {{ last_name.

That's what this library is mainly about — being able to detect, are outer heads and tails currently wrapping a single chunk of text, or are those heads and tails from separate chunks.

Also, this lib removes the leading/trailing empty clumps of empty heads/tails, with or without empty space:

// without whitespace:
`{{}}{{}} {{}}{{}} {{}}{{}} a {{}}{{}}` => `a`
// with whitespace:
`{{   \n   }}   \t   a   \n\n {{ \n\n \n\n   }}   \t\t` => `a`

You can configure heads and tails to be whatever you like, single string or array of them. Also, the length of the different heads in your given set can be different.

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API

remDup(str, [opts])

In other words, it's a function which takes two input arguments, second-one optional.

API - Input

Input argument	Type	Obligatory?	Description
`str`	String	yes	Source string upon which to perform the operation
`opts`	Plain object	no	Optional Options Object, see below for its API

If input string is not given, it will throw.

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An Optional Options Object

Optional Options Object's key	Type of its value	Default	Description
`heads`	Non-empty string or array of one or more non-empty strings	`[']`	Put here the way you mark the beginnings of your variables in a string.
`tails`	Non-empty string or array of one or more non-empty strings	`[']`	Put here the way you mark the endings of your variables in a string.