Limit Maximum Length of Line (max-len)

Very long lines of code in any language can be difficult to read. In order to aid in readability and maintainability many coders have developed a convention to limit lines of code to X number of characters (traditionally 80 characters).

// max-len: [1, 80, 4]; // maximum length of 80 characters
var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // too long

Rule Details

This rule is aimed at increasing code readability and maintainability by enforcing a line length convention. As such it will warn on lines that exceed the configured maximum.

The following patterns are considered warnings:

// max-len: [1, 80, 4]; // maximum length of 80 characters
var foo = { "bar": "This is a bar.", "baz": { "qux": "This is a qux" }, "difficult": "to read" }; // too long

The following patterns are not considered warnings:

// max-len: [1, 80, 4]; // maximum length of 80 characters
var foo = {
    "bar": "This is a bar.",
    "baz": {
        "qux": "This is a qux"
    },
    "difficult": "to read"
};

Options

The max-len rule has two required options:

• The total number of characters allowed on each line of code. This character count includes indentation.
• The character count to use whenever a tab character is encountered.

For example, to specify a maximum line length of 80 characters with each tab counting as 4 characters, use the following configuration:

"max-len": [2, 80, 4]

Related Rules

• complexity
• max-depth
• max-nested-callbacks
• max-params
• max-statements

Version

This rule was introduced in ESLint 0.0.9.

Resources

• Rule source
• Documentation source