if var is undefined javascript code example
Example 1: javascript check for undefined
if (typeof myVariable === 'undefined'){
}
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: test if is undefined javascript
let id;
if(typeof id === 'undefined') {
console.log("id is undefined...");
}
Example 4: check if variable is undefined or null jquery
if (variable == null) {
}
Example 5: nodejs check if variable is undefined
if ( typeof query !== 'undefined' && query )
{
}
else
{
}
Example 6: if not undefined javascript
if(typeof myVar !== "undefined")