web3.utils.fromWei

将给定的以wei为单位的值转换为其他单位的数值。

注意，wei是最小的以太单位，应当总是使用wei进行计算，仅在需要显示 时进行转换。

调用：

web3.utils.fromWei(number [, unit])

Converts any wei value into a ether value.

参数：

number - String|Number|BN: wei为单位的数值 unit - String，可选，默认值为ether，可选的单位有：

• noether: ‘0’
• wei: ‘1’
• kwei: ‘1000’
• Kwei: ‘1000’
• babbage: ‘1000’
• femtoether: ‘1000’
• mwei: ‘1000000’
• Mwei: ‘1000000’
• lovelace: ‘1000000’
• picoether: ‘1000000’
• gwei: ‘1000000000’
• Gwei: ‘1000000000’
• shannon: ‘1000000000’
• nanoether: ‘1000000000’
• nano: ‘1000000000’
• szabo: ‘1000000000000’
• microether: ‘1000000000000’
• micro: ‘1000000000000’
• finney: ‘1000000000000000’
• milliether: ‘1000000000000000’
• milli: ‘1000000000000000’
• ether: ‘1000000000000000000’
• kether: ‘1000000000000000000000’
• grand: ‘1000000000000000000000’
• mether: ‘1000000000000000000000000’
• gether: ‘1000000000000000000000000000’
• tether: ‘1000000000000000000000000000000’

返回值：

String|BN: 如果输入参数是数值或字符串，则返回字符串，否则返回BN.js对象

示例代码：

web3.utils.fromWei('1', 'ether');
> "0.000000000000000001"

web3.utils.fromWei('1', 'finney');
> "0.000000000000001"

web3.utils.fromWei('1', 'szabo');
> "0.000000000001"

web3.utils.fromWei('1', 'shannon');
> "0.000000001"