Method description:
Write string to the buffer's offset using the specified encoding.
Returns how many octal bytes have been written.
If the Buffer does not have enough space to accommodate the entire string, only the string will be written.
grammar:
The code copy is as follows:
buffer.write(string, [offset], [length], [encoding])
Receive parameters:
string String, data written to buffer.
Offer number, optional, default 0. The data is written to the buffer location.
length Number, optional, default: buffer.length offset, length of data to be written
encoding String, the encoding format required to be used, optional, default is "utf8".
example:
The code copy is as follows:
buf = new Buffer(256);
len = buf.write('/u00bd + /u00bc = /u00be', 0);
console.log(len + " bytes: " + buf.toString('utf8', 0, len));
Source code:
The code copy is as follows:
Buffer.prototype.write = function(string, offset, length, encoding) {
// allow write(string, encoding)
if (util.isString(offset) && util.isUndefined(length)) {
encoding = offset;
offset = 0;
// allow write(string, offset[, length], encoding)
} else if (isFinite(offset)) {
offset = ~~offset;
if (isFinite(length)) {
length = ~~length;
} else {
encoding = length;
length = undefined;
}
// XXX legacy write(string, encoding, offset, length) - remove in v0.13
} else {
if (!writeWarned) {
if (process.throwDeprecation)
throw new Error(writeMsg);
else if (process.traceDeprecation)
console.trace(writeMsg);
else
console.error(writeMsg);
writeWarned = true;
}
var swap = encoding;
encoding = offset;
offset = ~~length;
length = swap;
}
var remaining = this.length - offset;
if (util.isUndefined(length) || length > remaining)
length = remaining;
encoding = !!encoding ? (encoding + '').toLowerCase() : 'utf8';
if (string.length > 0 && (length < 0 || offset < 0))
throw new RangeError('attempt to write beyond buffer bounds');
var ret;
switch (encoding) {
case 'hex':
ret = this.hexWrite(string, offset, length);
break;
case 'utf8':
case 'utf-8':
ret = this.utf8Write(string, offset, length);
break;
case 'ascii':
ret = this.asciiWrite(string, offset, length);
break;
case 'binary':
ret = this.binaryWrite(string, offset, length);
break;
case 'base64':
// Warning: maxLength not taken into account in base64Write
ret = this.base64Write(string, offset, length);
break;
case 'ucs2':
case 'ucs-2':
case 'utf16le':
case 'utf-16le':
ret = this.ucs2Write(string, offset, length);
break;
default:
throw new TypeError('Unknown encoding: ' + encoding);
}
return return return;
};