/
prefer-add-event-listener.js
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/
prefer-add-event-listener.js
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'use strict';
const {isParenthesized} = require('eslint-utils');
const eventTypes = require('./shared/dom-events.js');
const {STATIC_REQUIRE_SOURCE_SELECTOR} = require('./selectors/index.js');
const MESSAGE_ID = 'prefer-add-event-listener';
const messages = {
[MESSAGE_ID]: 'Prefer `{{replacement}}` over `{{method}}`.{{extra}}',
};
const extraMessages = {
beforeunload: 'Use `event.preventDefault(); event.returnValue = \'foo\'` to trigger the prompt.',
message: 'Note that there is difference between `SharedWorker#onmessage` and `SharedWorker#addEventListener(\'message\')`.',
};
const getEventMethodName = memberExpression => memberExpression.property.name;
const getEventTypeName = eventMethodName => eventMethodName.slice('on'.length);
const fixCode = (fixer, sourceCode, assignmentNode, memberExpression) => {
const eventTypeName = getEventTypeName(getEventMethodName(memberExpression));
let eventObjectCode = sourceCode.getText(memberExpression.object);
if (isParenthesized(memberExpression.object, sourceCode)) {
eventObjectCode = `(${eventObjectCode})`;
}
let fncCode = sourceCode.getText(assignmentNode.right);
if (isParenthesized(assignmentNode.right, sourceCode)) {
fncCode = `(${fncCode})`;
}
const fixedCodeStatement = `${eventObjectCode}.addEventListener('${eventTypeName}', ${fncCode})`;
return fixer.replaceText(assignmentNode, fixedCodeStatement);
};
const shouldFixBeforeUnload = (assignedExpression, nodeReturnsSomething) => {
if (
assignedExpression.type !== 'ArrowFunctionExpression'
&& assignedExpression.type !== 'FunctionExpression'
) {
return false;
}
if (assignedExpression.body.type !== 'BlockStatement') {
return false;
}
return !nodeReturnsSomething.get(assignedExpression);
};
const isClearing = node => {
if (node.type === 'Literal') {
return node.raw === 'null';
}
if (node.type === 'Identifier') {
return node.name === 'undefined';
}
return false;
};
const create = context => {
const options = context.options[0] || {};
const excludedPackages = new Set(options.excludedPackages || ['koa', 'sax']);
let isDisabled;
const nodeReturnsSomething = new WeakMap();
let codePathInfo;
return {
onCodePathStart(codePath, node) {
codePathInfo = {
node,
upper: codePathInfo,
returnsSomething: false,
};
},
onCodePathEnd() {
nodeReturnsSomething.set(codePathInfo.node, codePathInfo.returnsSomething);
codePathInfo = codePathInfo.upper;
},
[STATIC_REQUIRE_SOURCE_SELECTOR](node) {
if (!isDisabled && excludedPackages.has(node.value)) {
isDisabled = true;
}
},
'ImportDeclaration > Literal'(node) {
if (!isDisabled && excludedPackages.has(node.value)) {
isDisabled = true;
}
},
ReturnStatement(node) {
codePathInfo.returnsSomething = codePathInfo.returnsSomething || Boolean(node.argument);
},
'AssignmentExpression:exit'(node) {
if (isDisabled) {
return;
}
const {left: memberExpression, right: assignedExpression} = node;
if (
memberExpression.type !== 'MemberExpression'
|| memberExpression.computed
) {
return;
}
const eventMethodName = getEventMethodName(memberExpression);
if (!eventMethodName || !eventMethodName.startsWith('on')) {
return;
}
const eventTypeName = getEventTypeName(eventMethodName);
if (!eventTypes.has(eventTypeName)) {
return;
}
let replacement = 'addEventListener';
let extra = '';
let fix;
if (isClearing(assignedExpression)) {
replacement = 'removeEventListener';
} else if (
eventTypeName === 'beforeunload'
&& !shouldFixBeforeUnload(assignedExpression, nodeReturnsSomething)
) {
extra = extraMessages.beforeunload;
} else if (eventTypeName === 'message') {
// Disable `onmessage` fix, see #537
extra = extraMessages.message;
} else {
fix = fixer => fixCode(fixer, context.getSourceCode(), node, memberExpression);
}
return {
node: memberExpression.property,
messageId: MESSAGE_ID,
data: {
replacement,
method: eventMethodName,
extra: extra ? ` ${extra}` : '',
},
fix,
};
},
};
};
const schema = [
{
type: 'object',
additionalProperties: false,
properties: {
excludedPackages: {
type: 'array',
items: {
type: 'string',
},
uniqueItems: true,
},
},
},
];
module.exports = {
create,
meta: {
type: 'suggestion',
docs: {
description: 'Prefer `.addEventListener()` and `.removeEventListener()` over `on`-functions.',
},
fixable: 'code',
schema,
messages,
},
};