判断自生属性与担任性

function foo() { this.name = ‘foo‘ this.sayHi = function () { console.log(‘Say Hi‘) } } foo.prototype.sayGoodBy = function () { console.log(‘Say Good By‘) } var myPro = new foo() console.log(myPro.name) // foo console.log(myPro.hasOwnProperty(‘name‘)) // true console.log(myPro.hasOwnProperty(‘toString‘)) // false console.log(myPro.hasOwnProperty(‘hasOwnProperty‘)) // fasle console.log(myPro.hasOwnProperty(‘sayHi‘)) // true console.log(myPro.hasOwnProperty(‘sayGoodBy‘)) // false console.log(‘sayGoodBy‘ in myPro) // true

判断自生属性是否存在

var o = new Object(); o.prop = ‘exists‘; function changeO() { o.newprop = o.prop; delete o.prop; } console.log(o.hasOwnProperty(‘prop‘)); // true changeO(); console.log(o.hasOwnProperty(‘prop‘)); // false

在看开源项目的过程中，经常会看到类似如下的源码。for...in循环东西的所有枚举属性，然后再使用hasOwnProperty()要领来忽略担任属性。

var buz = { fog: ‘stack‘ }; for (var name in buz) { if (buz.hasOwnProperty(name)) { alert("this is fog (" + name + ") for sure. Value: " + buz[name]); } else { alert(name); // toString or something else } }

js属性东西的hasOwnProperty要领