模块概览

Buffer是node的核心模块，开发者可以利用它来处理二进制数据，比如文件流的读写、网络请求数据的处理等。

简单示例

//创建
const buf = new Buffer([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);


//比较
// 例子一：编码一样，内容相同
var buf1 = Buffer.from('A');
var buf2 = Buffer.from('A');

console.log( buf1.equals(buf2) );  // true

// 例子二：编码一样，内容不同
var buf3 = Buffer.from('A');
var buf4 = Buffer.from('B');

console.log( buf3.equals(buf4) );  // false

// 例子三：编码不一样，内容相同
var buf5 = Buffer.from('ABC');  // <Buffer 41 42 43>
var buf6 = Buffer.from('414243', 'hex');

console.log(buf5.equals(buf6));

//连接

//拷贝
buf.copy(target[, targetStart[, sourceStart[, sourceEnd]]])

//查找
buf.indexOf(value[, byteOffset][, encoding])

//写入：buf.write(string[, offset[, length]][, encoding])
var buff = Buffer.alloc(20).fill('a');
console.log(buff.toString());  // aaaaaaaaaaaaaaaaaaaa

//转换
转成字符: buf.toString([encoding[, start[, end]]])
var buff = Buffer.from('hello');
console.log( buff.toString() );  // hello
console.log( buff.toString('utf8', 0, 2) );  // he

转成对象:buf.toJSON()
var buff = Buffer.from('hello');
console.log( buff.toJSON() );  // { type: 'Buffer', data: [ 104, 101, 108, 108, 111 ] }

//遍历：buf.values()、buf.keys()、buf.entries()
var buff = Buffer.from('abcde');

for(const key of buff.keys()){
    console.log('key is %d', key);
}
// key is 0
// key is 1
// key is 2
// key is 3
// key is 4

for(const value of buff.values()){
    console.log('value is %d', value);
}
// value is 97
// value is 98
// value is 99
// value is 100
// value is 101

for(const pair of buff.entries()){
    console.log('buff[%d] === %d', pair[0], pair[1]);
}
// buff[0] === 97
// buff[1] === 98
// buff[2] === 99
// buff[3] === 100
// buff[4] === 101

//截取：buf.slice([start[, end]])
var buff1 = Buffer.from('abcde');
console.log(buff1);  // <Buffer 61 62 63 64 65>

var buff2 = buff1.slice();
console.log(buff2);  // <Buffer 61 62 63 64 65>

var buff3 = buff1.slice(1, 3);
console.log(buff3);  // <Buffer 62 63>

buff3[0] = 97;  // parseInt(61, 16) ==> 97
console.log(buff1);  // <Buffer 62 63>