Question

I have an small array of data which i want to check if my values im checking against exist in the array together.

This is how the data looks like from my console.log(astar);

https://i.stack.imgur.com/XRKlU.jpg

My attempt was:

 console.log(astar); // display array info
     for (i=0; i < 50; i++){    
        for (j=0; j < 50; j++){ 
        if( i in astar && j in astar[i] ){
               abposx = getx(i);
               abposy = gety(j);
        ctx.fillStyle = "#000";
        ctx.fillRect (abposx,abposy,10,10);             
    }   

The idea is the “inner arrays” which have [0][1] positions im trying to see if “any” of them have [0] == i and [1] == j if so = true.

How should i alter it to work correctly & most efficiently – so that it will draw when it is found in the arrays

Answer 1

What you are currently doing is equivalent to

for (i=0; i < astar.length; i++)
    for (j=0; j < astar[i].length; j++) {
        abposx = getx(i);
        abposy = gety(j);
        ctx.fillStyle = "#000";
        ctx.fillRect(abposx,abposy,10,10);
    }

You may want:

for (i=0; i < astar.length; i++) {
    if (astar[i][0] > 50 || astar[i][1] > 50)
        continue;
    abposx = getx(astar[i][0]);
    abposy = gety(astar[i][1]);
    ctx.fillStyle = "#000";
    ctx.fillRect(abposx,abposy,10,10);
}

Looping through all coordinates is very inefficient and would need a third loop for searching in astar. Better loop through astar and paint what you can get.

The correct three-loop code would have been:

for (i=0; i < 50; i++)
    for (j=0; j < 50; j++)
        if (astar.some(function(item) {
            return item[0] == i && item[1] == j;
        }) {
            abposx = getx(i);
            abposy = gety(j);
            ctx.fillStyle = "#000";
            ctx.fillRect(abposx,abposy,10,10);
        }

(The some() loops through the array and returns true if an item matches the condition function. It equals the extended version posted by bfavaretto). Resulting in a performance of O(n^2.5)…