js if null then code example

Example 1: javascript check if null

if (variable === null) { //Executes only if variable is null but not undefined
  //Code here
}

if (variable == null) { //Executes if variable is null OR undefined
  //Code here
}

Example 2: javascript double question mark

let a = null;
const b = a ?? -1;		// Same as b = ( a != null ? a : -1 );
console.log(b);		  	// output: -1
//OR IF
let a = 9;
const b = a ?? -1;
console.log(b);  		// output: 9

//PS.,VERY CLOSE TO '||' OPERATION IN FUNCTION, BY NOT THE SAME

Example 3: js check null

if (Var === null) { 
//code goes here
}

Example 4: javascript check if undefined or null

// simple check do the job
if (myVar) {
 // comes here either myVar is not null,
 // or myVar is not undefined,
 // or myVar is not '' (empty string).
}