Javascript for Begginers - Construct 3

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Published on 5 Sep, 2021. Last updated 7 Sep, 2021
  1. Global and Local Variables

Accessing Global Variables e.g. I create a Global Variable named : Variable1 in event Sheet with value 100

I want to set the Variable1 to 10

runtime.globalvars.Variable1 = 10 ;

Now I want to call a value from a javascript variable that I created named : a

var a = 10;	
runtime.globalVars.Variable1 = a;

Now I want to set the variable "b" that I just create with the value that is in the Variable : Variable1 that is : 100

and I will see if it works with an alert that should show 100

var b = runtime.globalVars.Variable1 ;
alert(b)

Local Variables

Local Variables can only be used in the script block in the Event Sheet

I create a local variable named : Variable2

I created a new script file in the project tab , and set it to import for events , so we can call all the information in this file from event sheet , I created a variable : var c = 987654321; in this file

localVars.Variable2 = c // I call the Local Variable that I created and set it with the var c value
runtime.globalVars.Variable1 = localVars.Variable2// set the global variable with the local variable
alert(runtime.globalVars.Variable1)//the alert will show 987654321

You can create a variable in the script Block in the Event Sheet like bellow , and you can add more information in the same variable

For accessing the variables created in event sheet in script files you can use globalThis

var d = localVars.Variable2 + runtime.globalVars.Variable1 +10
alert(d);
//or
//globalThis.d = localVars.Variable2 + runtime.globalVars.Variable1 +10
//alert(globalThis.d);
  • Working with Javascript Variables

Set , Add or Subtract from variables

If we have a variable in script Named : Coins and want to add , set or subtract values after some condition like on colision or on tap , we can do it

let coins = 0; // declare the variable 
coins +=1 ; //add 1 to coins
coins =1 ; //set the coins to 1
coins -=1 ; //subtract 1 from coins

or

let value = 1; // insted of use 1 we can use this variable
coins +=value ; //add 1 to coins
coins =value ; //set the coins to 1
coins -=value ; //subtract 1 from coins

or

// or 
runtime.globalVars.Variable1 += value // the same to subtract and set

or

globalThis.coins = 0; // or you can use this
globalThis.coin +=value;

Functions and Ternary using Variables

runtime.globalVars.Variable2 = 2 > 1 ? " correct" : "Incorrect"// Correct
// functions
//-------------------------------------------------------------------------~

or

var v = 50;
var z = 45;
runtime.globalVars.Variable2 = myFunction(v,z);
function myFunction(p1, p2) {
  return p1 * p2; }  // The function returns the product of p1 and p2 : 2250

or

var person = {
  firstName : "Rafael",
  lastName  : "Trigo",
  age     : 99,
  eyeColor  : "pink"
};
runtime.globalVars.Variable2 = person.age + " " + person.firstName // returns 99 Rafael

or

var z = 20 ;
if ( z > runtime.globalVars.Variable2){
runtime.globalVars.Variable2 = 1000
} else{
runtime.globalVars.Variable2 = 50 + z

}

Now lets work with cases see the examples and change the value in the Variable2 to see the results , I set the Variable initialy with the value Pig2 so it will output " Some Pigs "

var Animal = null;
var Animal = runtime.globalVars.Variable2

switch (Animal) {
    case 'Dog':
	        alert('Dog');
        break;
    case 'Cat':
	        alert('Cat');
        break;
    case 'Bird':
	        alert('Bird');
        break;
    case 'Pig':
	case 'Pig1':
	case 'Pig2':
	case 'Pig3':
        alert('Some Pigs');
		
        break;
    case 'Any Animal':
    default:
        alert('Any Animal');
}
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