Why is this an issue?

Duplicated string literals make the process of refactoring complex and error-prone, as any change would need to be propagated on all occurrences.

Exceptions

To prevent generating some false-positives, literals having less than 10 characters are excluded as well as literals matching /^\w*$/.

The following patterns are also excluded based on AST context rather than string content:

• Import and export paths (e.g., import x from 'path')
• require() calls
• JSX attributes
• Type declarations and object properties
• Standalone string statements like directives (e.g., 'use strict';)

The ignoreStrings parameter is additive to these built-in exceptions, allowing you to specify additional strings to ignore via comma-separated values.

How to fix it

Use constants to replace the duplicated string literals. Constants can be referenced from many places, but only need to be updated in a single place.

Code examples

Noncompliant code example

With the default threshold of 3:

function run() {
    prepare("action_to_launch");  // Noncompliant - "action_to_launch" is duplicated 3 times
    execute("action_to_launch");
    release("action_to_launch");
}

function printInQuotes(a, b) {
  console.log("'" + a + "'" + b + "'");               // Compliant - literal "'" has less than 10 characters and is excluded
}

Compliant solution

var ACTION_1 = "action_to_launch";

function run() {
  prepare(ACTION_1);                               // Compliant
  execute(ACTION_1);
  release(ACTION_1);
}