Example 1: check data type in javascript
typeof("string"); //string
typeof(123); //number
Example 2: type javascirpt
console.log(typeof 42);
Example 3: javascript data types
/*JavaScript data types*/
//string
var string = 'ASCII text';
//int
var integer = 123456789;
//float
var float = 123.456;
//boolean, can be true or false
var t = true;
var f = false;
//undefined
var undef;//defaults to undefined
var undef = undefined;//not common, use null
//null
var nul = null;
//array
var arr = ['Hello','my','name','is','Dr.Hippo',123,null];
//object
var person = {'name':'John Smith','age':27};
//function
var fun = function(){
return 42;
}
Example 4: data types in javascript
//String Data Type
var strSingle = 'John'; //String with single quotes
var strDouble = "Bob"; //String with double quotes
//Number Data Type
var num = 25; //Integer
var flo = 80.5; //Floating-point number
var exp = 4.25e+6; //Exponential notation, this equates to 4250000
//Boolean Data Type
var isReading = true; //Yes, I'm reading
var isSleeping = false; //No, I'm not sleeping
//Undefined Data Type
var undef; //If a value is never assigned, any output will be 'undefined'
//Null Data Type
var noValue = null; //Null meaning that it is has no value, not the same as 0 or ""
//Object Data Type
var emptyObject = {};
var person = {"name": "Clark", "surname": "Kent", "age": "36"}; //The quotes around the propety name can be omitted if the property name is a valid JS name
var car = { //Same as person but easier to read
model: "BMW X3", //Example with quotes around property name ommitted
color: "white",
doors: 5
}
//Array Data Type
var emptyArray = []; //An array can be of any data types (string, number, boolean, etc.)
var array = ["One", "Two"] //String array, note the index of the first element is 0
//Function Data Type
var func = function() { //Calling the function: func();
alert("Code excuted"); //Outputs: Code executed
}
var funcVar = function(amount) { //Calling the function: funcVar(6);
alert("Code excuted " + amount + " times"); //Outputs: Code executed 6 times (if input was 6)
}
//Typeof Operator
typeof variable; //Returns the data type of the variable
Example 5: js data types
//There are 7 data types in JS
//They're split in two categories - (Primitives and Complex Types)
//Primives
string, number, boolean, null, undefined
//Complex types
Object, Function
Example 6: data types in javascript
1, 1.0 // Number
'String', "String"
true, false // Boolean
{id: 1;} // Object
[1, 2, 3] // Array