Why did targets.some not return true and prevent repeat of coordinates generated?
javascript
Ethan JacksonConsole output was as follows:
Targetting Pattern: Random About Target
Grid Coordinates: [ 20 , 10 ]
Salvo Coordinates:
21,12,
21,11,
17,8,
19,7,
21,12, <<== duplicate
20,12,
20,7,
18,12,
21,8,
22,11 <<== duplicate
Code Extract (1st approach): (using 'some' method)
function firePattern_onTargRand( col, row ){
var firePattern = 'Random About Target' ;
var target = [] ;
var targets = [] ;
var munitionsCost = 10 ;
for( i=1 ; i <= munitionsCost ; i++ ){
do {
target = [
col + getRandomInteger( 0, 6 ) -3 ,
row + getRandomInteger( 0, 6 ) -3
] ;
} while( targets.some(element => element === target ) ) ;
targets.push( target ) ;
} ;
console.log( "Targetting Pattern: " + `${firePattern}` + "\nGrid Coordinates: [" + ` ${col} , ${row} ` + "]\nSalvo Coordinates:\n" + targets ) ;
return targets ;
} ;
Code Extract (2nd approach): (direct comparison of array elements in loop)
function firePattern_onTargRand( col, row ){
var firePattern = 'Random About Target' ;
var target = [] ;
var targets = [] ;
var munitionsCost = 10 ;
var alreadyTargetted = false ;
for( i=1 ; i <= munitionsCost ; i++ ){
do {
target = [
col + getRandomInteger( 0, 6 ) -3 ,
row + getRandomInteger( 0, 6 ) -3
] ;
alreadyTargeted = false ;
for( let i = 0 ; i < targets.length ; i++ ){
if( targets[i] == target ) {
alreadyTargeted = true ;
} ;
} ;
} while( alreadyTargeted === true ) ;
} ;
targets.push( target ) ;
console.log( "Targetting Pattern: " + `${firePattern}` + "\nGrid Coordinates: [" + ` ${col} , ${row} ` + "]\nSalvo Coordinates:\n" + targets ) ;
return targets ;
} ;
Anyone know why I keep getting duplicates, when every pair of coordinates should be unique?
PS - I am very much a JavaScript novice.
Answer
You cannot compare objects and arrays. JS does not compare content of them but only pointers. You should compare row and col separately
function firePattern_onTargRand( col, row ){
var firePattern = 'Random About Target' ;
var target = [] ;
var targets = [] ;
var munitionsCost = 10 ;
var alreadyTargetted = false ;
for( i=1 ; i <= munitionsCost ; i++ ){
do {
target = [
col + getRandomInteger( 0, 6 ) -3 ,
row + getRandomInteger( 0, 6 ) -3
] ;
} while( targets.some(element => element.col === target.col && element.row === target.row ) ) ;
targets.push( target ) ;
} ;
console.log( "Targetting Pattern: " + `${firePattern}` + "\nGrid Coordinates: [" + ` ${col} , ${row} ` + "]\nSalvo Coordinates:\n" + targets ) ;
return targets ;
} ;To make it a little faster I propose using not array but object with keys:
function firePattern_onTargRand(col, row) {
var firePattern = 'Random About Target';
var target = [];
var targets = {};
var munitionsCost = 10;
var alreadyTargetted = false;
for (i = 1; i <= munitionsCost; i++) {
let key = '';
do {
target = [
col + getRandomInteger(0, 6) - 3,
row + getRandomInteger(0, 6) - 3
];
key = target.col + '_' + target.row
} while (targets[key]);
targets[key] = target;
};
//Now remove keys
targets = Object.values(targets)
console.log("Targetting Pattern: " + `${firePattern}` + "\nGrid Coordinates: [" + ` ${col} , ${row} ` + "]\nSalvo Coordinates:\n" + targets);
return targets;
};