Prefer that
for-in loops should include an if statement JS-0051
Anti-pattern
Minor
5 months ago
—
3 years old
Wrap the body of a for-in loop in an if statement with a hasOwnProperty guard
9712 d.__proto__ = b
9713 }) ||
9714 function (d, b) {
9715 for (const p in b) b.hasOwnProperty(p) && (d[p] = b[p]) 9716 })(d, b)
9717 }
9718 return function (d, b) {Wrap the body of a for-in loop in an if statement with a hasOwnProperty guard
8247 }),
8248 (e.idf = function (e, t) {
8249 let r = 0
8250 for (const i in e) i != '_index' && (r += Object.keys(e[i]).length) 8251 const n = (t - r + 0.5) / (r + 0.5)
8252 return Math.log(1 + Math.abs(n))
8253 }),Wrap the body of a for-in loop in an if statement with a hasOwnProperty guard
7617 },
7618 delegateEvents: function (t) {
7619 if ((t || (t = i.result(this, 'events')), !t)) return this
7620 for (const e in (this.undelegateEvents(), t)) { 7621 let n = t[e] 7622 if ((i.isFunction(n) || (n = this[n]), n)) { 7623 const r = e.match(P) 7624 this.delegate(r[1], r[2], n.bind(this)) 7625 } 7626 } 7627 return this
7628 },
7629 delegate: function (t, e, i) {Wrap the body of a for-in loop in an if statement with a hasOwnProperty guard
7132 let r
7133 const e = this._changing ? this._previousAttributes : this.attributes
7134 const n = {}
7135 for (const s in t) { 7136 const a = t[s] 7137 i.isEqual(e[s], a) || ((n[s] = a), (r = !0)) 7138 } 7139 return !!r && n
7140 },
7141 previous: function (t) {Wrap the body of a for-in loop in an if statement with a hasOwnProperty guard
7121 },
7122 clear: function (t) {
7123 const e = {}
7124 for (const n in this.attributes) e[n] = void 0 7125 return this.set(e, i.extend({}, t, { unset: !0 }))
7126 },
7127 hasChanged: function (t) {
Description
Looping over objects with a for in loop will include properties that are inherited through the prototype chain.
This behavior can lead to unexpected keys in your for loop.
Bad Practice
for (const key in foo) {
doSomething(key);
}
Recommended
for (const key in foo) {
if (Object.prototype.hasOwnProperty.call(foo, key)) {
doSomething(key);
}
}
for (const key of Object.keys(foo)) {
doSomething(key);
}