truthyfalsy.js

/**********************
 *  Truthy & falsy values
 ***/

// falsy values : undefined, null, 0, '', NaN
// truthy valyes: not falsy values

var height;
if (height || height === 0 ) {
	console.log('value defined');
} else {
 	console.log('undefined'); 
}

var txt = '';
if (txt || txt === 0 ) {
	console.log('value defined');
} else {
 	console.log('undefined str'); 
}
// string '23' converted to int so its true
var age = 23;
if (age == '23') {
	console.log('true');
}
// string '23' will not be converted to int so its false
if (age === '23') {
	console.log('true');
}else{
	console.log('false') 
}