prefer-await-to-callbacks.js
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/**
* Rule: prefer-await-to-callbacks
* Discourage using then() and instead use async/await.
*/
var errorMessage = 'Avoid callbacks. Prefer Async/Await.'
module.exports = function (context) {
function checkLastParamsForCallback (node) {
var len = node.params.length - 1
var lastParam = node.params[len]
if (lastParam && (lastParam.name === 'callback' || lastParam.name === 'cb')) {
context.report(lastParam, errorMessage)
}
}
function isInsideYieldOrAwait () {
return context.getAncestors().some(function (parent) {
return parent.type === 'AwaitExpression' || parent.type === 'YieldExpression'
})
}
return {
CallExpression: function (node) {
// callbacks aren't allowed
if (node.callee.name === 'cb' || node.callee.name === 'callback') {
context.report(node, errorMessage)
return
}
// thennables aren't allowed either
var args = node.arguments
var num = args.length - 1
var arg = num > -1 && node.arguments && node.arguments[num]
if (arg && arg.type === 'FunctionExpression' || arg.type === 'ArrowFunctionExpression') {
if (arg.params && arg.params[0] && arg.params[0].name === 'err') {
if (!isInsideYieldOrAwait()) {
context.report(arg, errorMessage)
}
}
}
},
FunctionDeclaration: checkLastParamsForCallback,
FunctionExpression: checkLastParamsForCallback,
ArrowFunctionExpression: checkLastParamsForCallback
}
}