1. What is TS
TypeScript is a superset of JavaScript. It mainly provides a type system and support for ES6. It is developed by Microsoft and the code is open source on GitHub. It can be compiled into pure JavaScript. The compiled JavaScript can run on any browser. The TypeScript compilation tool can run on any server and any system. TypeScript is open source.
Its first version was released in October 2012. After many updates, it has now become a force that cannot be ignored in the front-end community. It is not only widely used within Microsoft, but Angular2 and Vue3 also use TypeScript for development Language.
2. TS advantages and disadvantages
advantage:
(1) TypeScript is a superset of JavaScript, .js files can be directly renamed to .ts
(2) Even if there is no explicit type definition, type inferences can be made automatically
(3) Almost all types from simple to complex can be defined
(4) Even if TypeScript compiles errors, JavaScript files can be generated
(5) Compatible with third-party libraries, even if the third-party library is not written in TypeScript, you can write a separate type file for TypeScript to read
(6) The type system increases the readability and maintainability of the code
(7) Have an active community and support ES6 specifications
insufficient:
(1) There is a certain learning cost for students who have not been exposed to static languages, and they need to understand the concepts of Interfaces, Generics, Classes, Enums, etc.
(2) Some development costs may increase in the short term. After all, more definitions of types must be written. However, for a project that requires long-term maintenance, TypeScript can reduce its maintenance costs
(3) Integration into the build process requires some work
(4) It may not be perfect in combination with some libraries
3. Installation and use
The installation method of TypeScript command line tool is as follows:
npm install -g typescript
The above command will install the tsc command in the global environment. After the installation is complete, we can execute the tsc command anywhere.
Compile a TypeScript file: tsc hello.ts
At this time, a compiled file hello.js will be generated. TypeScript will only perform static checks. If errors are found, errors will be reported during compilation (js files will still be generated).
4. Basic
There are two types of JavaScript: primitive data types and object types.
The primitive data types include: Boolean, numeric, string, null, undefined, and the new type Symbol in ES6.
Boolean value:
Use boolean to define the Boolean value type: let isDone: boolean = false;
Note: The object created by the Boolean constructor is not a Boolean value: it is a Boolean object:
let createdByNewBoolean: boolean = new Boolean(1);
// index.ts(1,5): error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
let createdByNewBoolean: Boolean = new Boolean(1); //No error
Calling Boolean directly can also return a boolean type:
let createdByBoolean: boolean = Boolean(1); //No error
In TypeScript, boolean is the basic type in JavaScript, and Boolean is the constructor in JavaScript. Other basic types (except null and undefined) are the same.
5.Value:
Use number to define numeric types
Note: The hexadecimal notation of ES6 will be compiled into decimal by TS, and non-ES6 hexadecimal will be compiled according to the original hexadecimal.
let decLiteral: number = 6;
let hexLiteral: number = 0xf00d;
let binaryLiteral: number = 0b1010; // Binary representation in ES6
let octalLiteral: number = 0o744; // Octal notation in ES6
let notANumber: number = NaN;
let infinityNumber: number = Infinity;
After compilation:
var decLiteral = 6;
var hexLiteral = 0xf00d;
var binaryLiteral = 10; // Binary representation in ES6
var octalLiteral = 484; // Octal notation in ES6
var notANumber = NaN;
var infinityNumber = Infinity;
6.String:
Use string to define the string type:
let myName: string ='tan';
After compilation: let myName = "tan";
7.Null value:
JS has no concept of Void. In TS, void can be used to represent a function without any return value:
function alertName(): void {
alert('My name is tan');
}
A variable of type void is useless, because you can only assign it to undefined and null: let unusable: void = undefined;
8.Null and Undefined:
In TS, you can use null and undefined to define these two primitive data types:
let u: undefined = undefined;
let n: null = null;
Variables of type undefined can only be assigned a value of undefined, and variables of type null can only be assigned a value of null.
But undefined and null are subtypes of all types. In other words, variables of type undefined can be assigned to variables of type number:
let num: number = undefined;
Note: Variables of type void cannot be assigned to variables of type number.
9.Any value:
Any value (Any) is used to indicate that it is allowed to be assigned to any type, so it can be assigned to values of different types:
let myFavoriteNumber: any ='seven';
myFavoriteNumber = 7;
Access to any property on any value is allowed, and it is also allowed to call any method.
After declaring a variable as an arbitrary value, any operation on it will return any type of content.
Moreover, if the variable is not specified when its type is declared, it will be recognized as an arbitrary value type:
let something;
something ='seven';
something = 7;
与此原文有关的更多信息要查看其他翻译信息，您必须输入相应原文
|
|
|
|
How far(long) the transmitter cover?
The transmission range depends on many factors. The true distance is based on the antenna installing height , antenna gain, using environment like building and other obstructions , sensitivity of the receiver, antenna of the receiver . Installing antenna more high and using in the countryside , the distance will much more far.
EXAMPLE 5W FM Transmitter use in the city and hometown:
I have a USA customer use 5W fm transmitter with GP antenna in his hometown ,and he test it with a car, it cover 10km(6.21mile).
I test the 5W fm transmitter with GP antenna in my hometown ,it cover about 2km(1.24mile).
I test the 5W fm transmitter with GP antenna in Guangzhou city ,it cover about only 300meter(984ft).
Below are the approximate range of different power FM Transmitters. ( The range is diameter )
0.1W ~ 5W FM Transmitter ：100M ~1KM
5W ~15W FM Ttransmitter : 1KM ~ 3KM
15W ~ 80W FM Transmitter : 3KM ~10KM
80W ~500W FM Transmitter : 10KM ~30KM
500W ~1000W FM Transmitter : 30KM ~ 50KM
1KW ~ 2KW FM Transmitter : 50KM ~100KM
2KW ~5KW FM Transmitter : 100KM ~150KM
5KW ~10KW FM Transmitter : 150KM ~200KM
How to contact us for the transmitter?
Call me +8618078869184 OR
Email me [email protected]
1.How far you want to cover in diameter ?
2.How tall of you tower ?
3.Where are you from ?
And we will give you more professional advice.
About Us
FMUSER.ORG is a system integration company focusing on RF wireless transmission / studio video audio equipment / streaming and data processing .We are providing everything from advice and consultancy through rack integration to installation, commissioning and training.
We offer FM Transmitter, Analog TV Transmitter, Digital TV transmitter, VHF UHF Transmitter, Antennas, Coaxial Cable Connectors, STL, On Air Processing, Broadcast Products for the Studio, RF Signal Monitoring, RDS Encoders, Audio Processors and Remote Site Control Units, IPTV Products, Video / Audio Encoder / Decoder, designed to meet the needs of both large international broadcast networks and small private stations alike.
Our solution has FM Radio Station / Analog TV Station / Digital TV Station / Audio Video Studio Equipment / Studio Transmitter Link / Transmitter Telemetry System / Hotel TV System / IPTV Live Broadcasting / Streaming Live Broadcast / Video Conference / CATV Broadcasting system.
We are using advanced technology products for all the systems, because we know the high reliability and high performance are so important for the system and solution . At the same time we also have to make sure our products system with a very reasonable price.
We have customers of public and commercial broadcasters, telecom operators and regulation authorities , and we also offer solution and products to many hundreds of smaller, local and community broadcasters .
FMUSER.ORG has been exporting more than 15 years and have clients all over the world. With 13 years experience in this field ,we have a professional team to solve customer's all kinds of problems. We dedicated in supplying the extremely reasonable pricing of professional products & services. Contact email : [email protected]
Our Factory
We have modernization of the factory . You are welcome to visit our factory when you come to China.
At present , there are already 1095 customers around the world visited our Guangzhou Tianhe office . If you come to China , you are welcome to visit us .
At Fair
This is our participation in 2012 Global Sources Hong Kong Electronics Fair . Customers from all over the world finally have a chance to get together.
Where is Fmuser ?
You can search this numbers " 23.127460034623816,113.33224654197693 " in google map , then you can find our fmuser office .
FMUSER Guangzhou office is in Tianhe District which is the center of the Canton . Very near to the Canton Fair , guangzhou railway station, xiaobei road and dashatou , only need 10 minutes if take TAXI . Welcome friends around the world to visit and negotiate .
Contact: Sky Blue
Cellphone: +8618078869184
WhatsApp: +8618078869184
Wechat: +8618078869184
E-mail: [email protected]
QQ: 727926717
Skype: sky198710021
Address: No.305 Room HuiLan Building No.273 Huanpu Road Guangzhou China Zip:510620
|
|
|
|
English: We accept all payments , such as PayPal, Credit Card, Western Union, Alipay, Money Bookers, T/T, LC, DP, DA, OA, Payoneer, If you have any question , please contact me [email protected] or WhatsApp +8618078869184
-
PayPal.  www.paypal.com
We recommend you use Paypal to buy our items ,The Paypal is a secure way to buy on internet .
Every of our item list page bottom on top have a paypal logo to pay.
Credit Card.If you do not have paypal,but you have credit card,you also can click the Yellow PayPal button to pay with your credit card.
---------------------------------------------------------------------
But if you have not a credit card and not have a paypal account or difficult to got a paypal accout ,You can use the following:
Western Union.  www.westernunion.com
Pay by Western Union to me :
First name/Given name: Yingfeng
Last name/Surname/ Family name: Zhang
Full name: Yingfeng Zhang
Country: China
City: Guangzhou
|
---------------------------------------------------------------------
T/T . Pay by T/T (wire transfer/ Telegraphic Transfer/ Bank Transfer)
First BANK INFORMATION (COMPANY ACCOUNT):
SWIFT BIC: BKCHHKHHXXX
Bank name: BANK OF CHINA (HONG KONG) LIMITED, HONG KONG
Bank Address: BANK OF CHINA TOWER, 1 GARDEN ROAD, CENTRAL, HONG KONG
BANK CODE: 012
Account Name : FMUSER INTERNATIONAL GROUP LIMITED
Account NO. : 012-676-2-007855-0
---------------------------------------------------------------------
Second BANK INFORMATION (COMPANY ACCOUNT):
Beneficiary: Fmuser International Group Inc
Account Number: 44050158090900000337
Beneficiary's Bank: China Construction Bank Guangdong Branch
SWIFT Code: PCBCCNBJGDX
Address: NO.553 Tianhe Road, Guangzhou, Guangdong,Tianhe District, China
**Note: When you transfer money to our bank account, please DO NOT write anything in the remark area, otherwise we won't be able to receive the payment due to government policy on international trade business.
|
|
|
|
* It will be sent in 1-2 working days when payment clear.
* We will send it to your paypal address. If you want to change address, please send your correct address and phone number to my email [email protected]
* If the packages is below 2kg,we will be shipped via post airmail, it will take about 15-25days to your hand.
If the package is more than 2kg,we will ship via EMS , DHL , UPS, Fedex fast express delivery,it will take about 7~15days to your hand.
If the package more than 100kg , we will send via DHL or air freight. It will take about 3~7days to your hand.
All the packages are form China guangzhou.
* Package will be sent as a "gift" and declear as less as possible,buyer don't need to pay for "TAX".
* After ship, we will send you an E-mail and give you the tracking number.
|
|
|
For Warranty .
Contact US--->>Return the item to us--->>Receive and send another replace .
Name: Liu xiaoxia
Address: 305Fang HuiLanGe HuangPuDaDaoXi 273Hao TianHeQu Guangzhou China.
ZIP:510620
Phone: +8618078869184
Please return to this address and write your paypal address,name,problem on note: |
|
