'in' operator in JavaScript. String comparison [duplicate]

Question

Hi I'm new in JavaScript and i find a basic problem:

When I use that piece of code in Python:

'a' in 'aaa' 

I get True

When I do the same in JavaScript I get Error:

TypeError: Cannot use 'in' operator to search for 'a' in aaa

How to get similar result as in Python?

Answer 1

I think one way is to use String.indexOf()

'aaa' .indexOf('a') > -1

In javascript the in operator is used to check whether an object has a property

Answer 2

You're looking for indexOf.

'aaa'.indexOf('a') == 0 //if a char exists in the string, indexOf will return
                        // the index of the first instance of the char
'aaa'.indexOf('b') == -1 //if a char doesn't exist in the string, indexOf will return -1

Answer 3

Duplicate (How to check whether a string contains a substring in JavaScript?)

Try this:

var s = "aaaabbbaaa";
var result = s.indexOf("a") > -1;

Answer 4

From MDN:

The in operator returns true if the specified property is in the specified object.

You're interested in 'aaa'.indexOf('a').

Answer 5

try:

if('aaa'.search('a')>-1){
   //
}