'for in' error from jslint

[Andrew Poulos]

JSLint tells me that "The body of a for in should be wrapped in an if
statement to filter unwanted properties from the prototype." at
for (keys in this.vars) {

Could somebody explain what unwanted properties are being referred to?

Andrew Poulos

 

[Dmitry A. Soshnikov]

JSLint tells šme that "The body of a for in should be wrapped in an if
statement to filter unwanted properties from the prototype." at
š š for (keys in this.vars) {

Could somebody explain what unwanted properties are being referred to?

Andrew Poulos

"in" operator (11.8.7) analyses also prototype chain of an object.

Object.prototype.x = 10;
var a = {}; // "empty" object
for (var k in a) print(k); // x

so the hint says:

for (var k in a) if a.hasOwnProperty(k) {
print(k);
}

 

[Thomas 'PointedEars' Lahn]

JSLint tells me that "The body of a for in should be wrapped in an if
statement to filter unwanted properties from the prototype." at
for (keys in this.vars) {

Could somebody explain what unwanted properties are being referred to?

User-defined, thus enumerable, properties inherited from an object in the
prototype chain (usually the object constructor's prototype). Discussed ad
nauseam before. Google is your friend [psf 6.1], RTFM, RTFFAQ, STFW and so on!


PointedEars