js if not defined code example

Example 1: js if not undefined

if (typeof myVar !== "undefined") {
    console.log("myVar is DEFINED");
}

Example 2: checking if var is not defined js

if(typeof x !== 'undefined'){
  alert("Variable x is defined.");
}

Example 3: 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).
}

Example 4: undefined javascript check

if(undefinedElement === null) {
	console.log("Element is undefined");
}

Example 5: not defined javascript

/* Means something was not defined for example you wanted to print */ "X"
/* but X is not defined to defined you have to make a variable for it */
X = "Something" /* Once you define it it'll print the value successfully */