Verify whether the array contains the value entered by the user

Question

Verify whether the array contains the value entered by the user

Currently, I am utilizing an input field to gather user inputs and store them in an array.

The main objective is to verify whether the number inputted by the user already exists in the array. If it does, then the input should not be duplicated.

Below is my implementation:

if(e.keyCode === 43){

    var num = document.getElementById("numbers").value;
    var oks = [];

    // Set value of 'num'


    // Check if 'num' is present in the 'oks' array

    if( oks[num]==num ){

        alert("This number already exists."); 

    }
    else{

        oks[num.value]=num.value;

    }

    console.log(oks.value);


}

However, upon running the code above, the console log displays 'undefined'.

Please assist me in identifying the mistake in my approach.

Thank you for your support :)

javascript arrays

Answer 1

Answer №1

Your current code contains several errors that need to be addressed:

var oks = [];

The above code snippet creates an empty array every time the user inputs something, resulting in a useless check for the value's existence. To resolve this issue, you should declare the oks variable outside of the eventListener.

oks[num]

This code does not represent the value; rather, it refers to the element within the array with an index equal to the value, which are two distinct concepts.

num.value

The above statement is erroneous as the num variable represents a number, not a DOM element with a value attribute.

To rectify your problem, here is a potential solution:

if( oks.indexOf(num)>-1 ){
    alert("The value already exists.");
}
else{
    oks.push(num);
}

Answer 2

Your current code contains several errors that need to be addressed:

var oks = [];

The above code snippet creates an empty array every time the user inputs something, resulting in a useless check for the value's existence. To resolve this issue, you should declare the oks variable outside of the eventListener.

oks[num]

This code does not represent the value; rather, it refers to the element within the array with an index equal to the value, which are two distinct concepts.

num.value

The above statement is erroneous as the num variable represents a number, not a DOM element with a value attribute.

To rectify your problem, here is a potential solution:

if( oks.indexOf(num)>-1 ){
    alert("The value already exists.");
}
else{
    oks.push(num);
}

Answer 3

Answer №2

Here's a simple way to determine if a number is within an array:

if(oks.indexOf(num) != -1)

Alternatively, you can use the object oks and check if a field with a similar value exists, which may be more efficient:

var oks = [];

Since oks is initialized with each request and always empty, consider initializing it at a parent or global scope for better performance:

var oks = {};
// at a parent scope

if(e.keyCode === 43){

    var num = document.getElementById("numbers").value;
    // set num

    // Check if num is in the oks array
    if( oks{num} != undefined ){

        alert("It is already there."); 

    }
    else{

        oks[num]=true;

    }

    console.log(oks.num);

}

Answer 4

Here's a simple way to determine if a number is within an array:

if(oks.indexOf(num) != -1)

Alternatively, you can use the object oks and check if a field with a similar value exists, which may be more efficient:

var oks = [];

Since oks is initialized with each request and always empty, consider initializing it at a parent or global scope for better performance:

var oks = {};
// at a parent scope

if(e.keyCode === 43){

    var num = document.getElementById("numbers").value;
    // set num

    // Check if num is in the oks array
    if( oks{num} != undefined ){

        alert("It is already there."); 

    }
    else{

        oks[num]=true;

    }

    console.log(oks.num);

}

Verify whether the array contains the value entered by the user

Answer №1

Answer №2

Similar questions

The middleware is causing disruptions in the configuration of redis and express

Traversing JSON data in a recursive manner without definite knowledge of its size or nesting levels

Update the variables upon a click event following the completion of an AJAX request

Only allow scrolling if the number of child elements exceeds a certain limit

Having trouble getting the jQuery script to properly check file size in an HTML form before uploading?

Using Choices.js to inject live data into the select dropdown options

Guide to ensuring every request in an Express.js application contains a cookie

Adding a Javascript value to a WebSQL database

JavaScript does not acknowledge that one variable is greater than or equal to another

What is the recommended approach for embedding scripts within Angular templates?

Issue with exporting to Excel in AngularJS in Internet Explorer not functioning as expected

Utilizing Slots in Vue: Accessing Component Methods

Utilizing jQuery Mobile - Dividing content across multiple HTML files

A BMI calculator function that provides results in string format

Is there a way to monitor real-time updates without relying on setInterval or timeout functions?

Different Ways to Modify the Appearance of Angular's mat-slide-toggle and mat-checkbox

display a new feature immediately upon the user's login

Is there a way for me to insert a hook into the DOM after a promise has finished updating

Dynamic PHP content manipulated with jQuery Add/Remove functionality

Algorithm that continuously increases a given date by 3 months until it surpasses or matches the specified creation date