Javascript Property Name From Variable

Class Foo constructor static name. JavaScript provides a bunch of good ways to access object properties.

Var obj getElementById Demo var obj getElementById demo If possible use the same naming convention as JavaScript.

Javascript property name from variable. Const variable object property_name object property_name value. Var obj foo. The function name property of the javascript object is used to return the name of the function.

When using the same name for your properties the second property will overwrite the first. Let me name. See Properties with special characters or reserved words example.

Bracket notation variable key let key name. Const aliasIdentifier expressionidentifier. Foo c q null returns false foo c q false returns false foo c q undefined returns true.

After the destructuring the variable aliasIdentifier contains the property value. You have to create the object first and then assign each property separately. This does the exact same thing as the previous example.

Above class definition in ES2015 syntax will behave in Chrome or Firefox similar to the following snippet in ES5 syntax. MyObject myVar value. Var cx foo c x If a property is undefined an attempt to reference it will return undefined not null or false.

Identifier is the name of the property to access aliasIdentifier is the variable name and expression should evaluate to an object. ObjectName expression x age. Log a x.

There is no way to use that inside an object literal though. Where the dot notation is easier to read and write the square bracket notation offers much more flexibility since the value between the brackets can be any variable or expression. The name of the function which was given when the function was created is returned by Functionname.

Person x The expression must evaluate to a property name. We can add the property to JavaScript object using a variable as the name by using dot notation or bracket notation. Therefore if youve an objects property name stored in a JavaScript variable you can get its value using the square bracket notation.

Let a foo b 42 c. Samantha 3. Val Result 2.

Values pairs in JavaScript objects are called properties. Var myObject. In the objectproperty_name syntax the property_name is just a string or Symbol.

A true Duplicate property names. You can also set dynamic properties with the bracket syntax. So it can be any string including 1foo bar or even a space.

The dot property accessor syntax objectproperty works nicely when you know the variable ahead of time. Var myVar name. As shown in the second example this can modify existing objects too if property is already defined in the object value will be overwritten.

With a static name method Fooname no longer holds the actual class name but a reference to the name function object. This name property of the function is only readable and cannot be altered. The syntax for accessing the property of an object is.

There are two ways to access or get the value of a property from an object the dot notation like objfoo and the square bracket notation like obj foo. ObjectName property person age or. Bracket notation string key me name.

You can use the syntax to use an expression as the property name compared to the prop and prop. Let a x. Samantha 2.

These two JavaScript statements will produce different results. A consequence of using untidy HTML styles might result in JavaScript errors. You can access property x of c as follows.

When the property name is dynamic or is not a valid identifier a better alternative is square brackets property accessor. Shorthand property names ES2015 let o a b c In other words console. Var obj property1.

Therefore we cant obtain the class name for virtually any class with a static method property name. Function oab return o abo objkeyval. It does the same as.

Value syntaxes where they are always treated as strings.

Read more »