Meaning Exclamation Mark Javascript

What is double exclamation marks in javascript mean.

Meaning exclamation mark javascript. Function foo it turns it into an expression it is now a function expression. When you add an exclamation mark after variable property name you re telling to typescript that you re certain that value is not null or undefined. Returns false try it the exclamation mark doesn t have to be stuck to the variable or.

We would need an invocation foo to actually run the function. Think of it. The exclamation point is part of javascript s logical operators and is called the unary negation operator or more simply logical not it negates the expression that follows it.

It is now a function. I want to develop a nodejs app that scans some files in a given folder on the desktop. It s short way to cast a variable to be a boolean true or false value.

What does the double exclamation mark mean. Now when we add the seemingly innocuous exclamation mark. In some javascript code you might see the use of a double exclamation marks such as myanswer.

Here is a function declaration. Now when we add the seemingly innocuous exclamation mark. Is there even such an operator in javascript.

The double exclamation mark in javascript basically means convert to boolean invert then invert again. Function foo which has. If you have ever noticed a double exclamation mark in someone s javascript code you may be curious what it s for and what it does.