Cezary Waelnciuk
var myArray = [];
console.log(myArray.length);
// 0
var myArray = [];
console.log(myArray.length);
// 0
myArray[1000] = 'kapitan Cubasa';
console.log(myArray.length);
var myArray = [];
console.log(myArray.length);
// 0
myArray[1000] = 'kapitan Cubasa';
console.log(myArray.length);
// outputs 1001
var myArray = [10,20,30];
myArray.length = 5;
console.log(myArray);
var myArray = [10,20,30];
myArray.length = 5;
console.log(myArray);
>> (5) [10, 20, 30, undefined × 2]
var numbers = [1, 2, 3];
numbers.push(4);
console.log(numbers);
// [1, 2, 3, 4]
numbers.push(5, 6, 7);
console.log(numbers);
// [1, 2, 3, 4, 5, 6, 7]
var myarray = [1001, 2, 56, 29, 501, 1];
myarray.sort();
console.log(myarray);
var myarray = [1001, 2, 56, 29, 501, 1];
myarray.sort();
console.log(myarray);
>> [1, 1001, 2, 29, 501, 56]
var numbers = [1004, 501, 56, 26, 3];
numbers.sort(function(a, b) {
return a - b;
});
console.log(numbers);
>> [3, 26, 56, 501, 1004]
var myAssocArray = [];
myAssocArray["game"] = "mortal kombat";
myAssocArray["game"] = "Mortal Kombat";
myAssocArray["year"] = "1992";
myAssocArray2.game = "Mortal Kombat";
myAssocArray2.year = "1992";
console.log(typeof []);
console.log(typeof {});
console.log(typeof []);
// outputs: object
console.log(typeof {});
// outputs: object
function is_this_array (value) {
return value && typeof value
=== 'object'
&& value.constructor
=== Array;
}
console.log(is_this_array([]));
// outputs: true
console.log(is_this_array({}));
// outputs: false
for( var i in [ 44 , 33, 22 ] )
{ console.log( i ); };
for( var i in [ 44 , 33, 22 ] )
{ console.log( i ); };
>> 1
>> 2
>> 3
var tab = [ 44 , 33, 22 ];
tab.testowy = 1000;
for( var i in ) { console.log( i ); };
>> 1
>> 2
>> 3
>> testowy
var aaa = [2,"b"];
for (let value of aaa) {
value += 1;
console.log(value);
}
>> 3
>> b1
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth();
var yyyy = today.getFullYear();
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth();
var yyyy = today.getFullYear();
console.log(mm);
>> 8
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth() + 1;
var yyyy = today.getFullYear();
console.log(mm);
>> 9
0.1 + 0.2
0.1 + 0.2
>> 0.30000000000000004
function my() {
return {
head : 3
};
};
console.log(my());
//{head: 3}
function my() {
return
{
head : 3
};
};
console.log(my());
// undefined
if(cObject !== null &&
typeof(cObject) !== 'undefined') {
}
if(cObject !== null &&
typeof(cObject) !== 'undefined') {
}
>> throw error
if(typeof(myt) !== 'undefined'
&& myt !== null) {
}
>> works
var object1 = {
foo: "bar",
age: 66,
};
var object2 = {
foo: "bar",
age: 66
};
parseInt('16')
parseInt('16')
>> 16
parseInt('16')
>> 16
parseInt('16 Moto Myszy Z Marsa')
parseInt('16')
>> 16
parseInt('16 Moto Myszy Z Marsa')
>> 16
parseInt('Dwa 21')
parseInt('Dwa 21')
>> NaN
parseInt('Dwa 21')
>> NaN
parseInt('016')
parseInt('Dwa 21')
>> NaN
parseInt('016')
>> 14 //Old
>> 16 //New
Number("016") // returns 16
Number(016) // returns 14
parseInt('016',10)
console.log(typeof what);
var what = null;
console.log(typeof what);
console.log(typeof what);
// undefined
var what = null;
console.log(typeof what);
// object
typeof null;
// object
console.log(typeof 44);
console.log(typeof 1.5);
console.log(typeof NaN);
console.log(typeof Infinity);
console.log(typeof 44);
// number
console.log(typeof 1.5);
// number
console.log(typeof NaN);
// number
console.log(typeof Infinity);
// number
false == 'false';
false == 'false';
// false
false == 'false';
// false
false == '0';
false == 'false';
// false
false == '0';
// true
false == 'false';
// false
false == '0';
// true
0 == '';
false == 'false';
// false
false == '0';
// true
0 == '';
// true
false == undefined;
false == undefined;
// false
false == undefined;
// false
false == null;
false == undefined;
// false
false == null;
// false
false == undefined;
// false
false == null;
// false
null == undefined;
false == undefined;
// false
false == null;
// false
null == undefined;
// true
var ob1 = {};
var ob2 = {};
ob1 == ob2
var ob1 = {};
var ob2 = {};
ob1 == ob2
// false
var ob1 = {};
var ob2 = {};
ob1 == ob2
// false
ob1 === ob2
var ob1 = {};
var ob2 = {};
ob1 == ob2
// false
ob1 === ob2
// false
for (var i = 0; i < 10; i++) {
/* ... */
}
console.log(i);
// co to będzie?
for (var i = 0; i < 10; i++) {
/* ... */
}
console.log(i);
// co to będzie?
>> 10
bla = 2;
var bla;
// ...
// is implicitly understood as:
var bla;
bla = 2;
function myfn() {
console.log("przed:");
console.log(x);
if( true ) {
var x = 4;
console.log("w:");
console.log(x);
}
console.log("po:");
console.log(x);
console.log("koniec");
}
myfn();
function myfn() {
console.log("przed:");
console.log(x);
if( true ) {
var x = 4;
console.log("w:");
console.log(x);
}
console.log("po:");
console.log(x);
console.log("koniec");
}
myfn();
//przed: undefined
//w : 4
//po: 4
function myfn() {
console.log("przed:");
console.log(x);
if( false ) {
var x = 4;
console.log("w:");
console.log(x);
}
console.log("po:");
console.log(x);
console.log("koniec");
}
myfn();
function myfn() {
console.log("przed:");
console.log(x);
if( false ) {
var x = 4;
console.log("w:");
console.log(x);
}
console.log("po:");
console.log(x);
console.log("koniec");
}
myfn();
//przed: undefined
//w : undefined
//po: undefined
var ok = "global";
var cez = {
ok: "Tak",
myfunc : function() { return this.ok; }
};
console.log(cez.myfunc());
var meth = cez.myfunc;
console.log(meth());
var ok = "global";
var cez = {
ok: "Tak",
myfunc : function() { return this.ok; }
};
console.log(cez.myfunc());
var meth = cez.myfunc;
console.log(meth());
// "Tak"
// "Global"
var myString = "M My Mar";
var m1 =
myString.replace(' ',"___");
var m2 =
myString.replace(/ /g,"___");
console.log(m1);
console.log(m2);
var myString = "M My Mar";
var m1 =
myString.replace(' ',"___");
var m2 =
myString.replace(/ /g,"___");
console.log(m1); // "M___My Mar"
console.log(m2); // "M___My___Mar"