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require object keys to be sorted (sort-keys)

When declaring multiple properties, some developers prefer to sort property names alphabetically to be able to find necessary property easier at the later time. Others feel that it adds complexity and becomes burden to maintain.

Rule Details

This rule checks all property definitions of object expressions and verifies that all variables are sorted alphabetically.

Examples of incorrect code for this rule:

/*eslint sort-keys: "error"*/
/*eslint-env es6*/

let obj = {a: 1, c: 3, b: 2};
let obj = {a: 1, "c": 3, b: 2};

// Case-sensitive by default.
let obj = {a: 1, b: 2, C: 3};

// Non-natural order by default.
let obj = {1: a, 2: c, 10: b};

// This rule checks computed properties which have a simple name as well.
// Simple names are names which are expressed by an Identifier node or a Literal node.
const S = Symbol("s")
let obj = {a: 1, ["c"]: 3, b: 2};
let obj = {a: 1, [S]: 3, b: 2};

Examples of correct code for this rule:

/*eslint sort-keys: "error"*/
/*eslint-env es6*/

let obj = {a: 1, b: 2, c: 3};
let obj = {a: 1, "b": 2, c: 3};

// Case-sensitive by default.
let obj = {C: 3, a: 1, b: 2};

// Non-natural order by default.
let obj = {1: a, 10: b, 2: c};

// This rule checks computed properties which have a simple name as well.
let obj = {a: 1, ["b"]: 2, c: 3};
let obj = {a: 1, [b]: 2, c: 3};

// This rule ignores computed properties which have a non-simple name.
let obj = {a: 1, [c + d]: 3, b: 2};
let obj = {a: 1, ["c" + "d"]: 3, b: 2};
let obj = {a: 1, [`${c}`]: 3, b: 2};
let obj = {a: 1, [tag`c`]: 3, b: 2};

// This rule does not report unsorted properties that are separated by a spread property.
let obj = {b: 1, ...c, a: 2};

Options

{
    "sort-keys": ["error", "asc", {"caseSensitive": true, "natural": false, "minKeys": 2}]
}

The 1st option is "asc" or "desc".

  • "asc" (default) - enforce properties to be in ascending order.
  • "desc" - enforce properties to be in descending order.

The 2nd option is an object which has 3 properties.

  • caseSensitive - if true, enforce properties to be in case-sensitive order. Default is true.
  • minKeys - Specifies the minimum number of keys that an object should have in order for the object's unsorted keys to produce an error. Default is 2, which means by default all objects with unsorted keys will result in lint errors.
  • natural - if true, enforce properties to be in natural order. Default is false. Natural Order compares strings containing combination of letters and numbers in the way a human being would sort. It basically sorts numerically, instead of sorting alphabetically. So the number 10 comes after the number 3 in Natural Sorting.

Example for a list:

With natural as true, the ordering would be 1 3 6 8 10

With natural as false, the ordering would be 1 10 3 6 8

desc

Examples of incorrect code for the "desc" option:

/*eslint sort-keys: ["error", "desc"]*/
/*eslint-env es6*/

let obj = {b: 2, c: 3, a: 1};
let obj = {"b": 2, c: 3, a: 1};

// Case-sensitive by default.
let obj = {C: 1, b: 3, a: 2};

// Non-natural order by default.
let obj = {10: b, 2: c, 1: a};

Examples of correct code for the "desc" option:

/*eslint sort-keys: ["error", "desc"]*/
/*eslint-env es6*/

let obj = {c: 3, b: 2, a: 1};
let obj = {c: 3, "b": 2, a: 1};

// Case-sensitive by default.
let obj = {b: 3, a: 2, C: 1};

// Non-natural order by default.
let obj = {2: c, 10: b, 1: a};

insensitive

Examples of incorrect code for the {caseSensitive: false} option:

/*eslint sort-keys: ["error", "asc", {caseSensitive: false}]*/
/*eslint-env es6*/

let obj = {a: 1, c: 3, C: 4, b: 2};
let obj = {a: 1, C: 3, c: 4, b: 2};

Examples of correct code for the {caseSensitive: false} option:

/*eslint sort-keys: ["error", "asc", {caseSensitive: false}]*/
/*eslint-env es6*/

let obj = {a: 1, b: 2, c: 3, C: 4};
let obj = {a: 1, b: 2, C: 3, c: 4};

natural

Examples of incorrect code for the {natural: true} option:

/*eslint sort-keys: ["error", "asc", {natural: true}]*/
/*eslint-env es6*/

let obj = {1: a, 10: c, 2: b};

Examples of correct code for the {natural: true} option:

/*eslint sort-keys: ["error", "asc", {natural: true}]*/
/*eslint-env es6*/

let obj = {1: a, 2: b, 10: c};

minKeys

Examples of incorrect code for the {minKeys: 4} option:

/*eslint sort-keys: ["error", "asc", {minKeys: 4}]*/
/*eslint-env es6*/

// 4 keys
let obj = {
    b: 2,
    a: 1, // not sorted correctly (should be 1st key)
    c: 3,
    d: 4,
};

// 5 keys
let obj = {
    2: 'a',
    1: 'b', // not sorted correctly (should be 1st key)
    3: 'c',
    4: 'd',
    5: 'e',
};

Examples of correct code for the {minKeys: 4} option:

/*eslint sort-keys: ["error", "asc", {minKeys: 4}]*//
/*eslint-env es6*/

// 3 keys
let obj = {
    b: 2,
    a: 1,
    c: 3,
};

// 2 keys
let obj = {
    2: 'b',
    1: 'a',
};

When Not To Use It

If you don't want to notify about properties' order, then it's safe to disable this rule.

Related Rules

Compatibility

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