Check if a variable is undefined js code example
Example 1: js if not undefined
if (typeof myVar !== "undefined") {
console.log("myVar is DEFINED");
}
Example 2: javascript if undefined
if(typeof comment === 'undefined') {
alert('Variable "comment" is undefined.');
} else if(comment === null){
alert('Variable "comment" is null.');
}
Example 3: nodejs check if variable is undefined
if ( typeof query !== 'undefined' && query )
{
}
else
{
}
Example 4: javascript check if undefined or null
if (myVar) {
}