canonical
Version:
Canonical code style linter and formatter for JavaScript, SCSS and CSS.
93 lines (82 loc) • 2.48 kB
JavaScript
/**
* Disallows implicit type conversion.
*
* Type: `Array`
*
* Values: Array of quoted types
*
* #### Example
*
* ```js
* "disallowImplicitTypeConversion": ["numeric", "boolean", "binary", "string"]
* ```
*
* ##### Valid
*
* ```js
* x = Boolean(y);
* x = Number(y);
* x = String(y);
* x = s.indexOf('.') !== -1;
* ```
*
* ##### Invalid
*
* ```js
* x = !!y;
* x = +y;
* x = '' + y;
* x = ~s.indexOf('.');
* ```
*/
var assert = require('assert');
module.exports = function() {};
module.exports.prototype = {
configure: function(types) {
assert(Array.isArray(types), this.getOptionName() + ' option requires array value');
this._typeIndex = {};
for (var i = 0, l = types.length; i < l; i++) {
this._typeIndex[types[i]] = true;
}
},
getOptionName: function() {
return 'disallowImplicitTypeConversion';
},
check: function(file, errors) {
var types = this._typeIndex;
if (types.numeric || types.boolean || types.binary) {
file.iterateNodesByType('UnaryExpression', function(node) {
if (types.numeric && node.operator === '+') {
errors.add('Implicit numeric conversion', node.loc.start);
}
if (types.binary && node.operator === '~') {
errors.add('Implicit binary conversion', node.loc.start);
}
if (types.boolean &&
node.operator === '!' &&
node.argument.type === 'UnaryExpression' &&
node.argument.operator === '!'
) {
errors.add('Implicit boolean conversion', node.loc.start);
}
});
}
if (types.string) {
file.iterateNodesByType('BinaryExpression', function(node) {
if (node.operator !== '+') {
return;
}
// Do not report concatination for same string literals (#1538)
if (node.left.type === node.right.type) {
return;
}
if (
(node.left.type === 'Literal' && node.left.value === '') ||
(node.right.type === 'Literal' && node.right.value === '')
) {
errors.add('Implicit string conversion', node.loc.start);
}
});
}
}
};