How to get similar string by comparing two strings arrays?

Fiddle

Try something like

for (i = 0; i < array2.length; i++) {
        for (j = 0; j < array1.length; j++) {
            if (array1[j].toLowerCase().indexOf(array2[i].toLowerCase()) != -1) {
                arra3.push(array1[i]);
            }
        }
    }

You can loop through each array and compare the indexOf for each iteration. See the jsfiddle below.

var array1 = ["playing cricket", "Reading Books", "Flying"];

var array2 = ["cricket", "Books"];

var array3 = [];

for (var i = 0; i < array1.length; i++) {
    for (var x = 0; x < array2.length; x++) {
        console.log(array1[i] + ' ' + array2[x] + ': ' + similar(array1[i], array2[x]));
        if (similar(array1[i], array2[x])) {
            array3.push(array1[i] + ' : ' + array2[x]);
        }
    }
}

for(var c = 0; c < array3.length; c++){
document.write(array3[c] + '<br />');
}


function similar(a, b) {
    if (a.indexOf(b) !== -1 || b.indexOf(a) !== -1) {
        return true
    } else {
        return false;
    }
}

You could use Array#forEach and iterate both arrays for the check. Then collect common words in an object, to prevent more than one item of each.

var array1 = ["playing cricket", "Reading Books", "Flying"],
    array2 = ["cricket", "Books"],
    common = {};

array1.forEach(function (a) {
    var lowerA = a.toLocaleLowerCase();
    array2.forEach(function (b) {
        var lowerB = b.toLocaleLowerCase();
        if (lowerA.indexOf(lowerB) >= 0) {
            common[lowerB] = true;
        }
        if (lowerB.indexOf(lowerA) >= 0) {
            common[lowerA] = true;
        }
    });
});

console.log(Object.keys(common));

Another soulution could be to get the single words of the arrays, apply a bitmask for the array number and get the common out of the object for remembering.

var items = [["playing cricket", "Reading Books", "Flying"], ["cricket", "Books"]],
    count = {},
    common;

items.forEach(function (a, i) {
    a.forEach(function (b) {
        b.toLocaleLowerCase().split(' ').forEach(function (c) {
            this[c] = (this[c] || 0) | 1 << i;
        }, this);
    }, this);
}, count);

common = Object.keys(count).filter(function (k) {
    return count[k] === (1 << items.length) - 1;
});

console.log(common);

.as-console-wrapper { max-height: 100% !important; top: 0; }

you can also create a function for this

function find_similar_elements(a, b)
{
  var result = [];
  while(a.length>0 && b.length>0){
    if((a[0] > b[0]) || (a[0] < b[0])){
      var min,max; 
      if(a[0].length > b[0].length) {min = b[0]; max=a[0]}
      else{ min = a[0]; max=b[0] }

      if(max.indexOf(min) !== -1){
        result.push(min);
      } 
      a.shift();
      b.shift();

    } else{
      result.push(a.shift())
      b.shift();
    }
  }

  return result;
}

var array1 = ["playing cricket", "Reading Books", "Flying"]

var array2 = ["cricket", "Books"]

var result = find_similar_elements(array1, array2);

You can use Array#filter:

array1.filter(function(commonHobby) {
    for(var i = 0;i < array2.length;++i) {
        if(commonHobby.toLowerCase().indexOf(array2[i].toLowerCase()) !== -1) return true;
    }
});

In ES7 you can shorten it to:

array1.filter(commonHobby => array2.find(hobby => commonHobby.toLowerCase().includes(hobby.toLowerCase())));

You can compare two arrays (array1 and array2) using both filter and indexOf and find the common items:

array1.filter(function(n) { return array2.indexOf(n) != -1; });