我如何在不使用JavaScript的任何循环的情况下搜索元素

Question

I have an array like [1,2,3,4,5,6,7] how can I search for an element without using any loops and built-in methods in javascript ?

Thanks in advance

Answer 1

You could use a recursive approach and rest parameters ... for the array, without using some array methods.

 function find(search, array) { return function check(search, value, ...rest) { return search === value || rest.length && check(search, ... rest) || false; }(search, ...array); } console.log(find(1, [1, 2, 3, 4, 5, 6, 7])); console.log(find(42, [1, 2, 3, 4, 5, 6, 7])); 

Answer 2

You can use indexOf method to search for element. I hope this will help you.

 var array = [1,2,3,4,5,6,7]; var searchElement = 5; if(array.indexOf(searchElement)>-1) { console.log('element present in array'); } else { console.log('element not present in array'); } 

If you don't want to search all the elements. First iterate through all the elements and construct a object. The construction of object is one time process and use this object for searching an element.

 var array = [1,2,3,4,5,6,7]; var obj = {}; for(var i=0;i<array.length;i++) { if(obj.hasOwnProperty(array[i])) continue; obj[array[i]] = true; } var searchElement = 7; if(obj[searchElement] == true) { console.log("element present"); } else { console.log("element not present"); } 

Answer 3

The find() method returns the value of the first element in the array that satisfies the provided testing function. Otherwise undefined is returned.

var array1 = [5, 12, 8, 130, 44];

var found = array1.find(function(element) {
  return element > 10;
});

console.log(found);

Answer 4

You cannot search for an element in O(1) , however you can check if an element exist in a Set :

const set = new Set(array);
if(set.has(3)) console.log("3 is in array");

Answer 5

It is possible, but you must have an JavaScript Object like this:

var Obj = {
    'a':1,
    'b':2,
    'c':3,
    'd':4,
    'e':5
};

Without search you can access to your element like this:

console.log(Obj['a']);