Question

I’d like to check for a variable within my array. It works if the number matches my value directly. How can I get it to match the previous value if it’s below the match. From my code :

var assassin_bp = {
    fhr: { 7:8, 15:7, 27:6, 48:5, 86:4, 200:3 },
    fcr: { 8:15, 16:14, 27:13, 42:12, 65:11, 102:10, 174:9 }
}
var char_fhr = 48;
var fhr_frames = assassin_bp[ 'fhr' ][ [char_fhr] ]

with char_fhr worth 48, fhr_frames returns 5,
if char_fhr was worth 47 (or any number from 27 to 47), fhr_frames should return 6,
if char_fhr was worth 49 (or any number from 48 to 85), fhr_frames should return 5

I’m clueless on where to start. Can an object include a range? Should I have a function checking for it?

Answer 1

You need to iterate over the object properties and compare their names against your target value. See for...in ^[MDN] and Working with Objects ^[MDN].

function valueForClosestKey(obj, target) {
    // get all keys smaller than or equal to `target`
    var keys = [];
    for(var k in obj) {
        if(k <= target) {
            keys.push(k);
        }
    }

    // order keys in ascending order
    keys.sort(function(a, b) {
        return a - b;
    }); 
    // e.g. `keys` is now [7, 15, 27, 48]      

    // get the "closest" key, which is the last one in the array
    if(keys.length > 0) {
        return obj[keys.pop()];
    }
    // if there are no keys smaller than `target` (i.e. `keys` is empty),
    // we just don't return anything (implicitly returns `undefined`)
}

var value = valueForClosestKey(assassin_bp[ 'fhr' ], char_fhr);

It is necessary to extract and sort the keys this way because the order in which an object is iterated is implementation dependent. I.e. it is not guaranteed that the properties are in the correct numerical order.