Consider: if (someVar.hasOwnProperty('someProperty') ) { // Do something(); } else { // Do somethingElse(); } What is the right use/explanation of hasOwnProperty('someProperty')? Why can't we si...

Based on hasOwnProperty() method docs I wrote the following: const myObj = { prop1: 'val1', prop2: 'val2' } if (!myObj.hasOwnProperty('prop3')) { myObj.prop3 = 'val3' } But I'm getting this er...

I have the following code: let show = { createTag: false, updateFeature: false, createFeatureGroup: false, deleteFeature: false, deleteCycle: false, }; And I'm getting a value from the querys...

I'm trying to discover if an object has some properties and I'm having trouble using the hasOwnProperty method. I'm using the method on an array (I know the documentation states a string). The fo...

The new method Object.hasOwn() returns a boolean indicating whether the specified object has the indicated property as its own property but so does Object.prototype.hasOwnProperty(), what is the di...

If I understand correctly, each and every object in JavaScript inherits from the Object prototype, which means that each and every object in JavaScript has access to the hasOwnProperty function thr...

When is hasOwnProperty not required? The book JavaScript: The Good Parts includes the following which says that "it is usually necessary": The other form (called for in) enumerates the proper...

I want to check if an input element is a checkbox or text type. I know I can do this: //Type of input.. if ( input.type === "checkbox" ) //Contains the property.. if ( "checked" in input ) Bu...

Related to this question, i wanted to try out this var arr = [0,1,2,true,4,{"abc":123},6,7,{"def":456},9,[10]]; arr.filter(Object.hasOwnProperty,"abc");//outputs [0, 1, 2] arr.filter(Object.hasOwn...

I was hoping somebody could help clarify the hasOwnProperty() method with relation to Event Objects. I am trying to clone a mouse event (eventually this object will be passed to an iframe) I have ...

In some browsers, Object.keys() doesn't return all the keys that for-in loop with hasOwnProperty() returns. Is there a workaround without using for-in loops ? Also is there another object than wind...

Since hasOwnProperty has some caveats and quirks (window / extensive use in Internet Explorer 8 issues, etc.): Is there any reason to even use it? If simply testing if a property is undefined, is i...

I understand that the hasOwnProperty method in JavaScript exists to identify properties only of the current type, but there is something in the prototype chain here that is confusing to me. Let us...

Friends, I notice in Firefox v23.0.1 that, hasOwnProperty of HTMLElement(input,button..etc) doesn't work, button1.hasOwnProperty('id') = false I use for in to check: var str1 = ''; for (pp ...

It seems to me that there are four different ways I can determine whether a given object (e.g. foo) has a given property (e.g. bar) defined: if (foo.hasOwnProperty(bar)) { if ('bar' in foo) { if ...

This seems quite bizarre. Here's my experiment in the IE8 console: typeof obj1 // "object" obj1.hasOwnProperty // {...} typeof obj2 // "object" obj2.hasOwnProperty // undefined Any ideas as to...

I was talking about hasOwnProperty with another developer and how you are supposed to use it in for-in loops in javascript and he had a good question. When you do a for-in loop, why doesnt toString...