主对象 web3¶

在使用 web3 之前，请先确保正确引入web3.js。

web3¶

web3 对象提供了所有方法

示例¶

var Web3 = require('web3');
// create an instance of web3 using the HTTP provider.
// NOTE in mist web3 is already available, so check first if it's available before instantiating
var web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));

示例 using HTTP Basic Authentication¶

var Web3 = require('web3');
var web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545", 0, BasicAuthUsername, BasicAuthPassword));
//Note: HttpProvider takes 4 arguments (host, timeout, user, password)

web3.version¶

web3.version.api¶

web3.version.api

返回值¶

String - 以太坊js的api版本.

示例¶

var version = web3.version.api;
console.log(version); // "0.2.0"

web3.version.node¶

web3.version.node
// or async
web3.version.getNode(callback(error, result){ ... })

返回值¶

String - 客户端或节点的版本信息.

示例¶

var version = web3.version.node;
console.log(version); // "Mist/v0.9.3/darwin/go1.4.1"

web3.version.network¶

web3.version.network
// or async
web3.version.getNetwork(callback(error, result){ ... })

返回值¶

String - 网络协议版本.

示例¶

var version = web3.version.network;
console.log(version); // 54

web3.version.ethereum¶

web3.version.ethereum
// or async
web3.version.getEthereum(callback(error, result){ ... })

返回值¶

String - 以太坊的协议版本.

示例¶

var version = web3.version.ethereum;
console.log(version); // 60

web3.version.whisper¶

web3.version.whisper
// or async
web3.version.getWhisper(callback(error, result){ ... })

返回值¶

String - Twhisper协议的版本.

示例¶

var version = web3.version.whisper;
console.log(version); // 20

web3.isConnected¶

web3.isConnected()

检查是否与节点连接上

参数¶

无

返回值¶

Boolean:true表示已连接

示例¶

if(!web3.isConnected()) {

   // show some dialog to ask the user to start a node

} else {

   // start web3 filters, calls, etc

}

web3.setProvider¶

web3.setProvider(provider)

设置网络通信服务提供对象.

参数¶

none

返回值¶

undefined:通信服务提供对象

示例¶

web3.setProvider(new web3.providers.HttpProvider('http://localhost:8545')); // 8080 for cpp/AZ, 8545 for go/mist

web3.currentProvider¶

web3.currentProvider

如果已经设置了Provider，则返回当前的Provider。这个方法可以用来检查在使用mist浏览器等情况下已经设置过Provider，避免重复设置的情况.

返回值¶

Object - null 或已经设置的Provider对象;

示例¶

// Check if mist etc. already set a provider
if(!web3.currentProvider)
    web3.setProvider(new web3.providers.HttpProvider("http://localhost:8545"));

web3.reset¶

web3.reset(keepIsSyncing)

用来重置web3的状态。重置除了manager以外的其它所有东西。卸载filter，停止状态轮询

参数¶

flag``Boolean - 如果设置为true，将会卸载所有的filter，但会保留web3.eth.isSyncing()的状态轮询

返回值¶

undefined

示例¶

web3.reset();

web3.sha3¶

使用keccak-256哈希算法，计算给定字符串的哈希值

web3.sha3(string [, options])

参数¶

String - 传入的需要使用Keccak-256 SHA3算法进行哈希运算的字符串.
Object - 可选项设置。如果要解析的是hex格式的十六进制字符串。需要设置encoding为hex。因为JS中会默认忽略0x.

返回值¶

String - 使用Keccak-256 SHA3算法哈希过的结果.

示例¶

var hash = web3.sha3("Some string to be hashed");
console.log(hash); // "0xed973b234cf2238052c9ac87072c71bcf33abc1bbd721018e0cca448ef79b379"

var hashOfHash = web3.sha3(hash, {encoding: 'hex'});
console.log(hashOfHash); // "0x85dd39c91a64167ba20732b228251e67caed1462d4bcf036af88dc6856d0fdcc"

web3.toHex¶

web3.toHex(mixed);

Converts any value into HEX.

参数¶

val``String|Number|Object|Array|BigNumber - 需要转化为HEX的值。如果是一个对象或数组类型，将会先用JSON.stringify1进行转换成字符串。如果传入的是BigNumber2，则将得到对应的Number的HEX.

返回值¶

String - The hex string of mixed.

示例¶

var str = web3.toHex({test: 'test'});
console.log(str); // '0x7b2274657374223a2274657374227d'

web3.toAscii¶

将HEX字符串转为ASCII3字符串

web3.toAscii(hexString);

参数¶

1.hexString String - 十六进制字符串.

返回值¶

String - 给定十六进制字符串对应的ASCII码值.

示例¶

var str = web3.toAscii("0x657468657265756d000000000000000000000000000000000000000000000000");
console.log(str); // "ethereum"

web3.fromAscii¶

web3.fromAscii(string [, padding]);

将任何的ASCII码字符串转为HEX字符串.

参数¶

textString``String -ASCII码字符串.
padding``Number - 返回的字符串字节大小，不够长会自动填充.

返回值¶

String - 转换后的HEX字符串.

示例¶

var str = web3.fromAscii('ethereum');
console.log(str); // "0x657468657265756d"

var str2 = web3.fromAscii('ethereum', 32);
console.log(str2); // "0x657468657265756d000000000000000000000000000000000000000000000000"

web3.toDecimal¶

web3.toDecimal(hexString);

将一个十六进制转为一个十进制的数字.

参数¶

hexString``String - 十六进制字符.

返回值¶

Number - 传入字符串所代表的十六进制值.

示例¶

var number = web3.toDecimal('0x15');
console.log(number); // 21

web3.fromDecimal¶

web3.fromDecimal(number);

将一个数字，或者字符串形式的数字转为一个十六进制串.

参数¶

Number|String - 数字.

返回值¶

String - 给定数字对应的十六进制表示.

示例¶

var value = web3.fromDecimal('21');
console.log(value); // "0x15"

web3.fromWei¶

web3.fromWei(number, unit)

以太坊货币单位之间的转换。将以wei为单位的资金，转换为指定单位的数值:

Gwei
Kwei
Mwei/babbage/ether/femtoether
ether
finney/gether/grand/gwei
kether/kwei/lovelace/mether/micro
microether/milli/milliether
mwei/nano/nanoether
noether
picoether/shannon
szabo
tether
wei

参数¶

number``Number|String|BigNumber - 数字或BigNumber.
unitString` - 单位字符串.

返回值¶

String|BigNumber - Either a number string, or a BigNumber instance, depending on the given number parameter.

示例¶

var value = web3.fromWei('21000000000000', 'finney');
console.log(value); // "0.021"

web3.toWei¶

web3.toWei(number, unit)

将给定资金转换为以wei为单位的数值:

kwei/ada
mwei/babbage
gwei/shannon
szabo
finney
ether
kether/grand/einstein
mether
gether
tether

参数¶

Number|String|BigNumber - 数字或BigNumber.
String - 字符串单位.

返回值¶

String|BigNumber - 根据传入参数的不同，分别是字符串形式的字符串，或者是BigNumber.

示例¶

var value = web3.toWei('1', 'ether');
console.log(value); // "1000000000000000000"

web3.toBigNumber¶

web3.toBigNumber(numberOrHexString);

Converts a given number into a BigNumber instance.

See the note on BigNumber.

参数¶

Number|String - 数字或十六进制格式的数字.

返回值¶

BigNumber - BigNumber的实例.

示例¶

var value = web3.toBigNumber('200000000000000000000001');
console.log(value); // instanceOf BigNumber
console.log(value.toNumber()); // 2.0000000000000002e+23
console.log(value.toString(10)); // '200000000000000000000001'

web3.isAddress¶

web3.isAddress(HexString);

检查给定的字符串是否是有效的以太坊地址.

参数¶

String - 16进制字符串.

返回值¶

Boolean - 无效的地址返回false。对于全小写或全大写的有效地址字符串返回true。对于大小写混合的字符串, 该函数使用 web3.isChecksumAddress()进行检查.

示例¶

var isAddress = web3.isAddress("0x8888f1f195afa192cfee860698584c030f4c9db1");
console.log(isAddress); // true