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Use const where possible. #30

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199a0b0
Use `const` where possible.
NeilFraser Aug 12, 2023
a75616a
Merge pull request #1 from NeilFraser/NeilFraser-patch-1
NeilFraser Aug 12, 2023
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88 changes: 44 additions & 44 deletions src/main.js
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Original file line number Diff line number Diff line change
Expand Up @@ -18,12 +18,12 @@
*/
const _atob = function(string) {
// base64 character set, plus padding character (=)
let b64 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
const b64 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
// Regular expression to check formal correctness of base64 encoded strings
let b64re = /^(?:[A-Za-z\d+\/]{4})*?(?:[A-Za-z\d+\/]{2}(?:==)?|[A-Za-z\d+\/]{3}=?)?$/;
const b64re = /^(?:[A-Za-z\d+\/]{4})*?(?:[A-Za-z\d+\/]{2}(?:==)?|[A-Za-z\d+\/]{3}=?)?$/;
// remove data type signatures at the begining of the string
// eg : "data:audio/mid;base64,"
string = string.replace( /^.*?base64,/ , '');
string = string.replace(/^.*?base64,/ , '');
// atob can work with strings with whitespaces, even inside the encoded part,
// but only \t, \n, \f, \r and ' ', which can be stripped.
string = String(string).replace(/[\t\n\f\r ]+/g, '');
Expand All @@ -50,7 +50,7 @@
* [MidiParser description]
* @type {Object}
*/
const MidiParser = {
const MidiParser = {
// debug (bool), when enabled will log in console unimplemented events
// warnings and internal handled errors.
debug: false,
Expand All @@ -77,23 +77,23 @@
if(!File || !FileReader) throw new Error('The File|FileReader APIs are not supported in this browser. Use instead MidiParser.Base64() or MidiParser.Uint8()');

// validate provided element
if( _fileElement === undefined ||
if(_fileElement === undefined ||
!(_fileElement instanceof HTMLElement) ||
_fileElement.tagName !== 'INPUT' ||
_fileElement.type.toLowerCase() !== 'file'
_fileElement.type.toLowerCase() !== 'file'
){
console.warn('MidiParser.addListener() : Provided element is not a valid FILE INPUT element');
return false;
}
_callback = _callback || function(){};

_fileElement.addEventListener('change', function(InputEvt){ // set the 'file selected' event handler
if (!InputEvt.target.files.length) return false; // return false if no elements where selected
_fileElement.addEventListener('change', function(InputEvt){ // set the 'file selected' event handler
if (!InputEvt.target.files.length) return false; // return false if no elements where selected
console.log('MidiParser.addListener() : File detected in INPUT ELEMENT processing data..');
let reader = new FileReader(); // prepare the file Reader
reader.readAsArrayBuffer(InputEvt.target.files[0]); // read the binary data
reader.onload = function(e){
_callback( MidiParser.Uint8(new Uint8Array(e.target.result))); // encode data with Uint8Array and call the parser
const reader = new FileReader(); // prepare the file Reader
reader.readAsArrayBuffer(InputEvt.target.files[0]); // read the binary data
reader.onload = function(e){
_callback(MidiParser.Uint8(new Uint8Array(e.target.result))); // encode data with Uint8Array and call the parser
};
});
},
Expand All @@ -105,12 +105,12 @@
Base64 : function(b64String){
b64String = String(b64String);

let raw = _atob(b64String);
let rawLength = raw.length;
let t_array = new Uint8Array(new ArrayBuffer(rawLength));
const raw = _atob(b64String);
const rawLength = raw.length;
const t_array = new Uint8Array(new ArrayBuffer(rawLength));

for(let i=0; i<rawLength; i++) t_array[i] = raw.charCodeAt(i);
return MidiParser.Uint8(t_array) ;
return MidiParser.Uint8(t_array) ;
},

/**
Expand All @@ -119,7 +119,7 @@
* or 'false' if any error was generated.
*/
Uint8: function(FileAsUint8Array){
let file = {
const file = {
data: null,
pointer: 0,
movePointer: function(_bytes){ // move the pointer negative and positive direction
Expand All @@ -128,7 +128,7 @@
},
readInt: function(_bytes){ // get integer from next _bytes group (big-endian)
_bytes = Math.min(_bytes, this.data.byteLength-this.pointer);
if (_bytes < 1) return -1; // EOF
if (_bytes < 1) return -1; // EOF
let value = 0;
if(_bytes > 1){
for(let i=1; i<= (_bytes-1); i++){
Expand All @@ -142,21 +142,21 @@
},
readStr: function(_bytes){ // read as ASCII chars, the followoing _bytes
let text = '';
for(let char=1; char <= _bytes; char++) text += String.fromCharCode(this.readInt(1));
for(let char=1; char <= _bytes; char++) text += String.fromCharCode(this.readInt(1));
return text;
},
readIntVLV: function(){ // read a variable length value
let value = 0;
if ( this.pointer >= this.data.byteLength ){
if (this.pointer >= this.data.byteLength){
return -1; // EOF
}else if(this.data.getUint8(this.pointer) < 128){ // ...value in a single byte
value = this.readInt(1);
}else{ // ...value in multiple bytes
let FirstBytes = [];
const FirstBytes = [];
while(this.data.getUint8(this.pointer) >= 128){
FirstBytes.push(this.readInt(1) - 128);
}
let lastByte = this.readInt(1);
const lastByte = this.readInt(1);
for(let dt = 1; dt <= FirstBytes.length; dt++){
value += FirstBytes[FirstBytes.length - dt] * Math.pow(128, dt);
}
Expand All @@ -172,13 +172,13 @@
console.warn('Header validation failed (not MIDI standard or file corrupt.)');
return false; // Header validation failed (not MIDI standard or file corrupt.)
}
let headerSize = file.readInt(4); // header size (unused var), getted just for read pointer movement
let MIDI = {}; // create new midi object
const headerSize = file.readInt(4); // header size (unused var), getted just for read pointer movement
const MIDI = {}; // create new midi object
MIDI.formatType = file.readInt(2); // get MIDI Format Type
MIDI.tracks = file.readInt(2); // get ammount of track chunks
MIDI.track = []; // create array key for track data storing
let timeDivisionByte1 = file.readInt(1); // get Time Division first byte
let timeDivisionByte2 = file.readInt(1); // get Time Division second byte
const timeDivisionByte1 = file.readInt(1); // get Time Division first byte
const timeDivisionByte2 = file.readInt(1); // get Time Division second byte
if(timeDivisionByte1 >= 128){ // discover Time Division mode (fps or tpf)
MIDI.timeDivision = [];
MIDI.timeDivision[0] = timeDivisionByte1 - 128; // frames per second MODE (1st byte)
Expand All @@ -187,9 +187,9 @@

// ** read TRACK CHUNK
for(let t=1; t <= MIDI.tracks; t++){
MIDI.track[t-1] = {event: []}; // create new Track entry in Array
let headerValidation = file.readInt(4);
if ( headerValidation === -1 ) break; // EOF
MIDI.track[t-1] = {event: []}; // create new Track entry in Array
const headerValidation = file.readInt(4);
if (headerValidation === -1) break; // EOF
if(headerValidation !== 0x4D54726B) return false; // Track chunk header validation failed.
file.readInt(4); // move pointer. get chunk size (bytes length)
let e = 0; // init event counter
Expand All @@ -200,7 +200,7 @@
while(!endOfTrack){
e++; // increase by 1 event counter
MIDI.track[t-1].event[e-1] = {}; // create new event object, in events array
MIDI.track[t-1].event[e-1].deltaTime = file.readIntVLV(); // get DELTA TIME OF MIDI event (Variable Length Value)
MIDI.track[t-1].event[e-1].deltaTime = file.readIntVLV(); // get DELTA TIME OF MIDI event (Variable Length Value)
statusByte = file.readInt(1); // read EVENT TYPE (STATUS BYTE)
if(statusByte === -1) break; // EOF
else if(statusByte >= 128) laststatusByte = statusByte; // NEW STATUS BYTE DETECTED
Expand All @@ -215,8 +215,8 @@
//
if(statusByte === 0xFF){ // Meta Event type
MIDI.track[t-1].event[e-1].type = 0xFF; // assign metaEvent code to array
MIDI.track[t-1].event[e-1].metaType = file.readInt(1); // assign metaEvent subtype
let metaEventLength = file.readIntVLV(); // get the metaEvent length
MIDI.track[t-1].event[e-1].metaType = file.readInt(1); // assign metaEvent subtype
const metaEventLength = file.readIntVLV(); // get the metaEvent length
switch(MIDI.track[t-1].event[e-1].metaType){
case 0x2F: // end of track, has no data byte
case -1: // EOF
Expand Down Expand Up @@ -254,10 +254,10 @@
default :
// if user provided a custom interpreter, call it
// and assign to event the returned data
if( this.customInterpreter !== null){
MIDI.track[t-1].event[e-1].data = this.customInterpreter( MIDI.track[t-1].event[e-1].metaType, file, metaEventLength);
if(this.customInterpreter !== null){
MIDI.track[t-1].event[e-1].data = this.customInterpreter(MIDI.track[t-1].event[e-1].metaType, file, metaEventLength);
}
// if no customInterpretr is provided, or returned
// if no customInterpreter is provided, or returned
// false (=apply default), perform default action
if(this.customInterpreter === null || MIDI.track[t-1].event[e-1].data === false){
file.readInt(metaEventLength);
Expand All @@ -280,14 +280,14 @@

// if user provided a custom interpreter, call it
// and assign to event the returned data
if( this.customInterpreter !== null){
MIDI.track[t-1].event[e-1].data = this.customInterpreter( MIDI.track[t-1].event[e-1].type, file , false);
if(this.customInterpreter !== null){
MIDI.track[t-1].event[e-1].data = this.customInterpreter(MIDI.track[t-1].event[e-1].type, file , false);
}

// if no customInterpretr is provided, or returned
// if no customInterpreter is provided, or returned
// false (=apply default), perform default action
if(this.customInterpreter === null || MIDI.track[t-1].event[e-1].data === false){
let event_length = file.readIntVLV();
const event_length = file.readIntVLV();
MIDI.track[t-1].event[e-1].data = file.readInt(event_length);
if (this.debug) console.info('Unimplemented 0xF exclusive events! data block readed as Integer');
}
Expand All @@ -312,8 +312,8 @@
default:
// if user provided a custom interpreter, call it
// and assign to event the returned data
if( this.customInterpreter !== null){
MIDI.track[t-1].event[e-1].data = this.customInterpreter( MIDI.track[t-1].event[e-1].metaType, file , false);
if(this.customInterpreter !== null){
MIDI.track[t-1].event[e-1].data = this.customInterpreter(MIDI.track[t-1].event[e-1].metaType, file , false);
}

// if no customInterpretr is provided, or returned
Expand All @@ -336,7 +336,7 @@
* to be manually increased
* If you want default action to be performed, return false
*/
customInterpreter : null // function( e_type , arrayByffer, metaEventLength){ return e_data_int }
customInterpreter : null // function(e_type , arrayByffer, metaEventLength){ return e_data_int }
};


Expand All @@ -352,5 +352,5 @@
}


})();

})();