CODEWITHSUNDEEP
javascriptarrays
Jonas Chinagorom
Jonas Chinagorom

Reputation: 1

How to make indexof() differentiate between two like numbers in an array

I have an array say 

x = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]

I am using javascript indexof() to check if an element exist or not in the array and if it doesn't exits to do something....

my problem is that when an element like, 1,2,3,4,5,6 doesn't exist in the array, it still judge elements like 10 for 1, 12 for 2, 13 for 3, 14 for 4, 15 for 5, 16 for 6. and so it will still return that the element exists eventhough it is not there

eg: 

if x = [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]

this will still not work as it will see 10 as 1

if(data1.indexOf(1)===-1){											document.getElementById("s1").style.backgroundColor= "red";
    $("input[name='seat1']").attr("disabled", "disabled");
}

Upvotes: 0

Views: 90

Answers (4)

shanks
shanks

Reputation: 922

I would convert them to strings like this. 

function existsInArray(numberArrays, number){
       const numAsStrings = numberArrays.join(',').split(',')
       return numAsStrings.indexOf(String(number)) > -1
    }
    
    console.log(existsInArray([1,2,3,4,5,6,33], 33))
    //true
    
    console.log(existsInArray([1,2,3,4,5,6,33], 34))
    //false

Hope this helps.

Upvotes: 0

mvw
mvw

Reputation: 5105

Your example snippet is not helpful, as it does not show the data ("data1") you are working on.

The behaviour you describe is not the one which one gets with your example array: 

x = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16];

alert("indexOf(1):" + x.indexOf(1));
alert("indexOf(10):" + x.indexOf(10));
alert("indexOf(0):" + x.indexOf(0));

It works as intended.

Your real data proably contains strings and not integers.

Upvotes: 0

Emil S. Jørgensen
Emil S. Jørgensen

Reputation: 6366

Array.indexOf works in any browser > IE8: MDN Browser compatibility

Polyfill It if you need to support anything.

// POLYFILL TO SUPPORT ANY BROWSER
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf#Polyfill
// Production steps of ECMA-262, Edition 5, 15.4.4.14
// Reference: http://es5.github.io/#x15.4.4.14
if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function(searchElement, fromIndex) {

    var k;

    // 1. Let o be the result of calling ToObject passing
    //    the this value as the argument.
    if (this == null) {
      throw new TypeError('"this" is null or not defined');
    }

    var o = Object(this);

    // 2. Let lenValue be the result of calling the Get
    //    internal method of o with the argument "length".
    // 3. Let len be ToUint32(lenValue).
    var len = o.length >>> 0;

    // 4. If len is 0, return -1.
    if (len === 0) {
      return -1;
    }

    // 5. If argument fromIndex was passed let n be
    //    ToInteger(fromIndex); else let n be 0.
    var n = +fromIndex || 0;

    if (Math.abs(n) === Infinity) {
      n = 0;
    }

    // 6. If n >= len, return -1.
    if (n >= len) {
      return -1;
    }

    // 7. If n >= 0, then Let k be n.
    // 8. Else, n<0, Let k be len - abs(n).
    //    If k is less than 0, then let k be 0.
    k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);

    // 9. Repeat, while k < len
    while (k < len) {
      // a. Let Pk be ToString(k).
      //   This is implicit for LHS operands of the in operator
      // b. Let kPresent be the result of calling the
      //    HasProperty internal method of o with argument Pk.
      //   This step can be combined with c
      // c. If kPresent is true, then
      //    i.  Let elementK be the result of calling the Get
      //        internal method of o with the argument ToString(k).
      //   ii.  Let same be the result of applying the
      //        Strict Equality Comparison Algorithm to
      //        searchElement and elementK.
      //  iii.  If same is true, return k.
      if (k in o && o[k] === searchElement) {
        return k;
      }
      k++;
    }
    return -1;
  };
}

// TEST ARRAY
var arr = [0,1,2,3,4,6,7,8,9,10,12,13,14,16,17,18,20]
// TESTS
var offset = 0;
for(var i = 0; i <= 20; i++) {
  if(arr.indexOf(i) === -1) {
    console.log(i, "not found");
  } else  {
    console.log(i, "found")
  }
}

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386604

You could parse the string and use indexOf as array method.

JSON.parse(data1).indexOf(1) ...

Upvotes: 1

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