Check if value exists in an object in array of objects

Question

I am trying to write the code of following algorithm

• I have an array of active_id (array)
• ID coming from url (string)
• if value of ID does not exist in active_id array
  • run the function A()
• else do nothing.

Note - function A() should be run only once.

I tried writing the code

for (var i = 0; i < activeIds.length; i++) {
    if (activeIds[i] != uid) {
         A();  //This is running multiple times.
    }

I tried using while loop

var i = 0;
while (activeIds[i] != uid) {
     A();  //This is running multiple times again.
    i++;
}

There is something i am missing. not able to figure it out.

Answer 1

You can just use indexOf function which will return -1 if element is not exist on array and positive number start 0 till array (length -1) if element exist:

if (activeIds.indexOf(uid) == -1) {
    A();  
}

function A(); 

Answer 2

You can use indexOf, like this:

if( activeIds.indexOf(id) < 0 ) A();

Answer 3

If you want to invoke function A() only if the a particular ID (uid) does not exist in your array activeIds, you may want to alter your loop approach with this:

if (activeIds.filter(function(n){ return n===uid }).length==0){
    A();
}

Where you have a definition of function A() ready to use already.

Side note You syntax with function A(){} is just defining the function A but it's not going to run it. If you want to define and run it once, you may do:

(function A(){
   // logic goes here
})();

Answer 4

You can use array.indexof() function in order to find the value. It will look something like that:

if(activeIds.indexOf(uid) === -1){
    A();
}

Answer 5

Try this, code.

var i=0;
var isMatchFound = false;

while (activeIds.length >= i) {
  if(activeIds[i] ==uid){
    isMatchFound = true;
    break;
}
 i++;
}

if(isMatchFound){
   //Call Function A
    A();
}

Hope this will help