init-declarations.js
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/**
* @fileoverview A rule to control the style of variable initializations.
* @author Colin Ihrig
* @copyright 2015 Colin Ihrig. All rights reserved.
*/
"use strict";
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Checks whether or not a given node is a for loop.
* @param {ASTNode} block - A node to check.
* @returns {boolean} `true` when the node is a for loop.
*/
function isForLoop(block) {
return block.type === "ForInStatement" ||
block.type === "ForOfStatement" ||
block.type === "ForStatement";
}
/**
* Checks whether or not a given declarator node has its initializer.
* @param {ASTNode} node - A declarator node to check.
* @returns {boolean} `true` when the node has its initializer.
*/
function isInitialized(node) {
var declaration = node.parent;
var block = declaration.parent;
if (isForLoop(block)) {
if (block.type === "ForStatement") {
return block.init === declaration;
}
return block.left === declaration;
}
return Boolean(node.init);
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = function(context) {
var MODE_ALWAYS = "always",
MODE_NEVER = "never";
var mode = context.options[0] || MODE_ALWAYS;
var params = context.options[1] || {};
//--------------------------------------------------------------------------
// Public API
//--------------------------------------------------------------------------
return {
"VariableDeclaration:exit": function(node) {
var kind = node.kind,
declarations = node.declarations;
for (var i = 0; i < declarations.length; ++i) {
var declaration = declarations[i],
id = declaration.id,
initialized = isInitialized(declaration),
isIgnoredForLoop = params.ignoreForLoopInit && isForLoop(node.parent);
if (id.type !== "Identifier") {
continue;
}
if (mode === MODE_ALWAYS && !initialized) {
context.report(declaration, "Variable '" + id.name + "' should be initialized on declaration.");
} else if (mode === MODE_NEVER && kind !== "const" && initialized && !isIgnoredForLoop) {
context.report(declaration, "Variable '" + id.name + "' should not be initialized on declaration.");
}
}
}
};
};
module.exports.schema = {
"anyOf": [
{
"type": "array",
"items": [
{
"enum": [0, 1, 2]
},
{
"enum": ["always"]
}
],
"minItems": 1,
"maxItems": 2
},
{
"type": "array",
"items": [
{
"enum": [0, 1, 2]
},
{
"enum": ["never"]
},
{
"type": "object",
"properties": {
"ignoreForLoopInit": {
"type": "boolean"
}
},
"additionalProperties": false
}
],
"minItems": 1,
"maxItems": 3
}
]
};