JS API

Global Objects

console

The console module provides a simple debugging console that is similar to the JavaScript console mechanism provided by web browsers.

The global console can be used without calling require('console').

console.info([...args])

  • ...args <any>

    The console.info() function is an alias for console.log().

console.log([...args])

  • ...args <any>

    Print args to Nebulas Logger at level info.

console.debug([...args])

  • ...args <any>

    Print args to Nebulas Logger at level debug.

console.warn([...args])

  • ...args <any>

    Print args to Nebulas Logger at level warn.

console.error([...args])

  • ...args <any>

    Print args to Nebulas Logger at level error.

LocalContractStorage

The LocalContractStorage module provides a state trie based storage capability. It accepts string only key value pairs. And all data are stored to a private state trie associated with current contract address, only the contract can access them.

interface Descriptor {
    // serialize value to string;
    stringify?(value: any): string;

    // deserialize value from string;
    parse?(value: string): any;
}

interface DescriptorMap {
    [fieldName: string]: Descriptor;
}

interface ContractStorage {
    // get and return value by key from Native Storage.
    rawGet(key: string): string;
    // set key and value pair to Native Storage,
    // return 0 for success, otherwise failure.
    rawSet(key: string, value: string): number;

    // define a object property named `fieldname` to `obj` with descriptor.
    // default descriptor is JSON.parse/JSON.stringify descriptor.
    // return this.
    defineProperty(obj: any, fieldName: string, descriptor?: Descriptor): any;

    // define object properties to `obj` from `props`.
    // default descriptor is JSON.parse/JSON.stringify descriptor.
    // return this.
    defineProperties(obj: any, props: DescriptorMap): any;

    // define a StorageMap property named `fieldname` to `obj` with descriptor.
    // default descriptor is JSON.parse/JSON.stringify descriptor.
    // return this.
    defineMapProperty(obj: any, fieldName: string, descriptor?: Descriptor): any;

    // define StorageMap properties to `obj` from `props`.
    // default descriptor is JSON.parse/JSON.stringify descriptor.
    // return this.
    defineMapProperties(obj: any, props: DescriptorMap): any;

    // delete key from Native Storage.
    // return 0 for success, otherwise failure.
    del(key: string): number;

    // get value by key from Native Storage,
    // deserialize value by calling `descriptor.parse` and return.
    get(key: string): any;

    // set key and value pair to Native Storage,
    // the value will be serialized to string by calling `descriptor.stringify`.
    // return 0 for success, otherwise failure.
    set(key: string, value: any): number;
}

interface StorageMap {
    // delete key from Native Storage, return 0 for success, otherwise failure.
    del(key: string): number;

    // get value by key from Native Storage,
    // deserialize value by calling `descriptor.parse` and return.
    get(key: string): any;

    // set key and value pair to Native Storage,
    // the value will be serialized to string by calling `descriptor.stringify`.
    // return 0 for success, otherwise failure.
    set(key: string, value: any): number;
}

BigNumber

The BigNumber module use the bignumber.js, a JavaScript library for arbitrary-precision decimal and non-decimal arithmetic. The contract can use BigNumber directly to handle the value of the transaction and other values transfer.

var value = new BigNumber(0);
value.plus(1);
...

Blockchain

The Blockchain module provides a object for contracts to obtain transactions and blocks executed by the current contract. Also, the NAS can be transferred from the contract and the address check is provided.

Blockchain API:

// current block 
Blockchain.block;

// current transaction, transaction's value/gasPrice/gasLimit auto change to BigNumber object
Blockchain.transaction;

// transfer NAS from contract to address
Blockchain.transfer(address, value);

// verify address
Blockchain.verifyAddress(address);

properties:

  • block: current block for contract execution

    • timestamp: block timestamp

    • hash: block hash

    • height: block height

  • transaction: current transaction for contract execution

    • hash: transaction hash

    • from: transaction from address

    • to: transaction to address

    • value: transaction value, a BigNumber object for contract use

    • nonce: transaction nonce

    • timestamp: transaction timestamp

    • gasPrice: transaction gasPrice, a BigNumber object for contract use

    • gasLimit: transaction gasLimit, a BigNumber object for contract use

  • transfer(address, value): transfer NAS from contract to address

    • params:

      • address: nebulas address to receive NAS

      • value: transfer value, a BigNumber object

    • return:

      • 0: transfer success

      • 1: transfer failed

  • verifyAddress(address): verify address

    • params:

      • address: address need to check

    • return:

      • 1: address is valid

      • 0: address is invalid

Example to use:

'use strict';

var SampleContract = function () {
    LocalContractStorage.defineProperties(this, {
        name: null,
        count: null
    });
    LocalContractStorage.defineMapProperty(this, "allocation");
};

SampleContract.prototype = {
    init: function (name, count, allocation) {
        this.name = name;
        this.count = count;
        allocation.forEach(function (item) {
            this.allocation.put(item.name, item.count);
        }, this);
        console.log('init: Blockchain.block.coinbase = ' + Blockchain.block.coinbase);
        console.log('init: Blockchain.block.hash = ' + Blockchain.block.hash);
        console.log('init: Blockchain.block.height = ' + Blockchain.block.height);
        console.log('init: Blockchain.transaction.from = ' + Blockchain.transaction.from);
        console.log('init: Blockchain.transaction.to = ' + Blockchain.transaction.to);
        console.log('init: Blockchain.transaction.value = ' + Blockchain.transaction.value);
        console.log('init: Blockchain.transaction.nonce = ' + Blockchain.transaction.nonce);
        console.log('init: Blockchain.transaction.hash = ' + Blockchain.transaction.hash);
    },
    transfer: function (address, value) {
        var result = Blockchain.transfer(address, value);
        console.log("transfer result:", result);
        Event.Trigger("transfer", {
            Transfer: {
                from: Blockchain.transaction.to,
                to: address,
                value: value
            }
        });
    },
    verifyAddress: function (address) {
         var result = Blockchain.verifyAddress(address);
        console.log("verifyAddress result:", result);
    }
};

module.exports = SampleContract;

Event

The Event module records execution events in contract. The recorded events are stored in the event trie on the chain, which can be fetched by FetchEvents method in block with the execution transaction hash. All contract event topics have a chain.contract. prefix before the topic they set in contract.

Event.Trigger(topic, obj);

  • topic: user-defined topic

  • obj: JSON object

You can see the example in SampleContract before.

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