check if not null or undefined javascript code example
Example 1: javascript if undefined
if(typeof comment === 'undefined') {
alert('Variable "comment" is undefined.');
} else if(comment === null){
alert('Variable "comment" is null.');
}
Example 2: javascript not null
if (variable !== null) {
console.log("Var is NOT null");
}
Example 3: javascript check if undefined or null or empty string
// simple check do the job
if (myString) {
// comes here either myString is not null,
// or myString is not undefined,
// or myString is not '' (empty).
}
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).
}