将数组与键对比JavaScript对象中的键

Question

I have an array with keys like ["1", "5", "9"] And I have an object with the same keys, something like this: selections: { "5": {}, "12": {} }

What is the easiest way to get a boolean value out of it. It should return true if any of the keys in the array is present in my object. I am using angular and lodash, is there any smart solution for this or do I need to do a loop for it? And if I do a loop, what is the most efficient way?

Answer 1

Did you try to use hasOwnProperty()?

function check() {
  var selections = { "5": {}, "12": {} };
  return ["1", "5", "9"].filter(function(value) {
    return selections.hasOwnProperty(value);
  }).length > 0;
}

Answer 2

var selections = { "5": {}, "12": {} };
var array = ["1", "5", "9"];

array.some(key => selections.hasOwnProperty(key));

Answer 3

Just a single line of code:

 var array = ["1", "5", "9"], obj = { "5": {}, "12": {} }, any = array.some(function (a) { return a in obj; }); document.write(any); 

Answer 4

var keys = ["1", "5", "9"]; 
var selections = {"5": {}, "12": {}};   

function hasAnyKey(keys, selections) {
  for (var i = 0; i < keys.length; i++) {
    if (selections[keys[i]]) {
      return true;
    }
  }
  return false;
};

hasAnyKey(keys, selections);

This solution will return as soon as there is 1 match, which equates to returning true when there is at least 1 match, which is what you want. In theory, this will work faster than the solutions with Array.prototype.filter for larger inputs.

Answer 5

Array.prototype.some() executes the callback function once for each element present in the array until it finds one where callback returns a true value. If such an element is found, some() immediately returns true. Otherwise, some() returns false. Array.prototype.some() is in ECMAScript 1.5 and should work just about anywhere.

 function compareArrayToObject(array, obj) { return array.some(function (a) { return a in obj; }); } var array = ["1", "5", "9"]; var obj = { "5": {}, "12": {} }; var result = compareArrayToObject(array, obj); document.write(result);