Tuesday, 6 February 2018

Node Js Buffer module examples with script code

Node Js Buffer module examples with script code

Question: What is buffer module?
Buffer class provides instances to store binary data similar to an array of integers. Buffer class is a global class that can be accessed in an application.


Question: How to create an empty buffer object?
var bufferData=Buffer.alloc(1024); //1024 bytes



Question: How to write in buffer object?
var bufferData.write('this is string'); //write only string



Question: How to create an array of buffer?
var buf1 = Buffer.from('1');
var buf2 = Buffer.from('2');
var buf3 = Buffer.from('3');
var bufferData = [buf1, buf2, buf3];
console.log(bufferData);//

OR
arrayObject=[];
arrayObject.push(Buffer.from('1'));
arrayObject.push(Buffer.from('2'));
arrayObject.push(Buffer.from('3'));
console.log(arrayObject);



Question: What is concat? How to concate the buffer data?
Concatenates an array of Buffer objects into one Buffer object
var buf1 = Buffer.from('1');
var buf2 = Buffer.from('2');
var buf3 = Buffer.from('3');
var bufferData = [buf1, buf2, buf3];
bufferData=Buffer.concat(bufferData);

OR
arrayObject=[];
arrayObject.push(Buffer.from('1'));
arrayObject.push(Buffer.from('2'));
arrayObject.push(Buffer.from('3'));
bufferData=Buffer.alloc(1024);
bufferData = Buffer.concat(arrayObject);
console.log(bufferData);



Question: How to compare two buffer?
var buf1 = Buffer.from('abc');
var buf2 = Buffer.from('abc');
var compare1 = Buffer.compare(buf1, buf2);
console.log(compare1); //0

var buf1 = Buffer.from('a');
var buf2 = Buffer.from('b');
var compare2 = Buffer.compare(buf1, buf2);
console.log(compare2); //-1

var buf1 = Buffer.from('b');
var buf2 = Buffer.from('a');
var compare3 = Buffer.compare(buf1, buf2);
console.log(compare3); //1



Question: How to check if data is buffer?
Buffer.isBuffer(obj);//true|false



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