Not operator

Category:Math

Not operator

Category: Math

Returns false if the expression is true; otherwise, returns true.

You can stick a NOT (!) in front of any boolean expression to invert its result. This opens the door to express the same logical statements in different ways.

Examples

// Truth table for the boolean NOT operator.
console.log(!true);
console.log(!false);

Example: Take Your Temperature Check (two different ways) for temperature in a good range or not.

// Check for temperature in a good range or not.
textLabel("tempLabelID", "What is your temperature?");
textInput("tempID", "");
button("buttonID", "Submit");
textLabel("tempMessageID1", "");
textLabel("tempMessageID2", "");
onEvent("buttonID", "click", function(event) {
  setText("tempMessageID1","");
  setText("tempMessageID2","");  
  var temp = getText("tempID");
  if (!(temp >= 98 && temp <= 99.5) ) {
    setText("tempMessageID1", "You may be sick.");
  }
  else {
    setText("tempMessageID1", "Your temperature is fine.");
  }
  if (!(temp >= 98) || !(temp <= 99.5) ) {
    setText("tempMessageID2", "You may be sick.");
  }
  else {
    setText("tempMessageID2", "Your temperature is fine.");
  }
});

Example: Working 9 to 5 Determines if it is currently working hours.

// Determines if it is currently working hours.
function IsWorkingHours() {
    var now = new Date();
    var hours = now.getHours();
    var workHours = false;
    if (hours >= 9 && hours < 17) {
        workHours = true; 
    }
    return workHours;
}

if (!IsWorkingHours()) {
    console.log('take a break');
} else {
    console.log('get to work');
}

Syntax

!expression

Parameters

Name Type Required? Description
expression boolean Yes The boolean expression to invert the result of.

Returns

Boolean true or false

Tips

  • Some complex decisions can sometimes be rewritten to use an ! operator. It is fine to choose whichever reads clearest.

Found a bug in the documentation? Let us know at documentation@code.org

Syntax

!__

Returns

Boolean (true/false) value

Found a bug in the documentation? Let us know at documentation@code.org