javascript check if undefined or null 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 check if undefined or null
if( typeof myVar === 'undefined' || myVar === null ){
}
Example 3: javascript check for null variables
var myVar=null;
if(myVar === null){
}
if (typeof myVar === 'undefined'){
}
Example 4: javascript check if undefined or null or empty string
if (myString) {
}
Example 5: javascript check if undefined or null
if (myVar) {
}
Example 6: javascript check undefined or null
var myVar=null;
if(myVar === null){
}
if (typeof myVar === 'undefined'){
}