javascript笔记

1.We can write out anything to the console with:console.log();

2.定义变量:

var strength = '50,000 pounds';

var age = 20;

var hasPet = true;

 

3.获取字符串长度:

"yourName".length;

 

4.confirm("I am ready to go.");

These boxes can beused on websites to confirm things with users. You've probablyseen them pop up when you try to delete important things or leave a websitewith unsaved changes.

5.  You can ask forinput with a prompt.

Examples:

prompt("What is your name?");

 

6.=== Equal to

!== Not equalto

7. The number part isa little strange. To select for the "he" in "hello", you would write this:

"hello".substring(0, 2);

 

8.函数

( 1 定义

var divideByThree= function (number) {

    var val = number / 3;

    console.log(val);

};

( 2 使用

divideByThree(10);

 

9.

for (var i = 1; i < 11; i++) {

    /* your code here */;

}

 

10.数组

var arrayName = [data,data, data];

 

11.定义object

( 1

var myObject = {

    key: value,

    key: value,

    key: value

};

( 2

var myObj = {

    type: 'fancy',

    disposition: 'sunny'

};

var myObj = new Object();

 

myObj.type =“zzl”;

 

12.

You can add objects directly to friends, like this:

var friends = {

    bill: {},

    steve: {}

};

Or with the bracket ([]) or dot(.) notation, like this:

friends[bill] ={};

friends.steve ={};

Or with Object constructors, like this:

var friends =new Object();

 

friends.bill =new Object();

friends.steve =new Object();

Notice that"bill" and "steve" are not capitalized!

 

13.add parameters

var friends = {

    bill: {

        firstName:"Bill",

        lastName:"Gates",

        number:"(206) 555-5555",

        address: ['One Microsoft Way','Redmond','WA','98052']

    }

};

 

1.定义类

var someObj = {

 

aProperty: value,

someMethod: function(some, params) {}

 

};

Whenwe call someObj.someMethod(some,values);, thecode between the curly brackets { } willrun.

2.引用内部参数

var james = {

    job:"programmer",

    married:false,

    sayJob:function() {

        //complete this method

       console.log("Hi, I work as a " + this.job);

    }

};

 

3.

An advantage of bracket notation is that we are not restrictedto just using strings in the brackets. We can also use variables whose valuesare property names:

var someObj = {propName: someValue};

var myProperty = "propName";

someObj[myProperty];

The last line is exactlythe same as usingsomeObj["propName"];.

 

4.获取参数的类型

var someObject = {someProperty: someValue};

console.log( typeof someObject );

 

 

5.

var myObj = {

    // finishmyObj

    name:"zzl"

};

 

console.log( myObj.hasOwnProperty('name')); // should print true

console.log( myObj.hasOwnProperty('nickname') ); //should print false

 

6.

Now let's learn how to work with all the properties that belongto an object. First, let's define an object:

var dog = {

species: "bulldog",

age: 3,

color: brown

};

To print out all elements, we can use afor/in loop, like this:

for(var property in dog) {

  console.log(property);

}

In the loop we use console.log to print out each key. Rememberthe "property" bit can be any placeholder name you like.

 

7.打印出类的参数

for(var x in dog) {

console.log(dog[x]);

}

 

8.

In general, if you want to add a method to a class such that allmembers of the class can use it, we use the following syntax to extend the prototype:

className.prototype.newMethod =

function() {

statements;

};

      

 

9.构造器

functionPerson(name,age) {

  this.name = name;

  this.age = age;

};

 

10.声明继承关系

Set the Penguin class's prototype to a new instance of Animal by adding this line after youmake the constructor:

Penguin.prototype = new Animal();

 

11.获取类里的private变量

function Person(first,last,age) {

   this.firstname = first;

   this.lastname = last;

   this.age = age;

   var bankBalance = 7500;

 

   this.getBalance= function() {

      // your codeshould return the bankBalance

      return bankBalance;

   };

}

 

12.

Using constructor notation, aproperty declared as this.property = "someValue;"will be public,whereas a property declared with var property= "hiddenValue;" will be private.