I am making a game with obstacles at different x and y coordinates and I am put all the obstacles into a list like so:

var list = [{x:200, y:400},{x:120, y:400},{x:170, y:400}];

I am trying to find the object with the greatest x value. Is there some kind of max() function for objects like these? So I can find the max object? Max X: 200 Also please do forgive my if my questions are sloppy and have some errors, I am still a child at age 12 and do not find these errors often.

CodePudding user response：

Firstly, what you showed is not a proper object in JavaScript. I guess the proper list you want to present is like below?

var list = [
  { x: 200, y: 400 },
  { x: 120, y: 400 },
  { x: 170, y: 400 }
]

Then, if you want to get the max value, try this:

function getMaxValue(list, key) {
    const keyArray = list.map(l => l[key])
    return Math.max(keyArray)
}

By using above function, if you want to find the max x, try getMaxValue(list, 'x'). If you want to find the max y, try getMaxValue(list, 'y')

CodePudding user response：

You can use Array.reduce:

var list = [{
  x: 200,
  y: 400
}, {
  x: 120,
  y: 400
}, {
  x: 170,
  y: 400
}];

const res = list.reduce((a,b) => a = b.x > a.x ? b : a, list[0])
console.log(res)

<iframe name="sif1" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

CodePudding user response：

To find the object with the greatest value of x, use the Array#filter() method to only return object(s) that have the max value of x as determined by Math.max( ...arr ). The 0 index ([0]) ensures an object is returned; if there are more than two objects, the first will be returned:

const oMaxX = list.filter(obj => obj.x === Math.max( ...list.map(a => a.x) ) )[0];

DEMO

Show code snippet

const list = [
  { x: 200, y: 400 },
  { x: 120, y: 400 },
  { x: 170, y: 400 }
];

const oMaxX = list.filter(obj => obj.x === Math.max( ...list.map(a => a.x) ) )[0];

console.log( oMaxX );

<iframe name="sif2" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>