Tips for verifying the presence of a value in a select box

Question

Tips for verifying the presence of a value in a select box

Are there alternative approaches to using a for loop to determine if a value is present in a select box with JavaScript?

I am interested in something similar to

document.getElementById('selbox').valueExists('myval');

javascript dom

Answer 1

Answer №1

using ES6 syntax:

const option = document.getElementById('selbox').querySelector('[value="' + my_value + '"]');

this code snippet will locate the first element with the attribute value="my_value".

Note: Apologies for any spanglish in my explanation :)

Answer 2

using ES6 syntax:

const option = document.getElementById('selbox').querySelector('[value="' + my_value + '"]');

this code snippet will locate the first element with the attribute value="my_value".

Note: Apologies for any spanglish in my explanation :)

Answer 3

Answer №2

The functionality of the select element cannot be extended, meaning that a separate function is required to determine if a value exists within it.

An alternative approach without using a loop entails...

function CheckSelectHasValue(select, value) {
    var elem = document.getElementById(select);

    if (elem !== null) {
        return (elem.innerHTML.indexOf('value="' + value + '"') > -1);
    } else {
        return false;
    }
}

Answer 4

The functionality of the select element cannot be extended, meaning that a separate function is required to determine if a value exists within it.

An alternative approach without using a loop entails...

function CheckSelectHasValue(select, value) {
    var elem = document.getElementById(select);

    if (elem !== null) {
        return (elem.innerHTML.indexOf('value="' + value + '"') > -1);
    } else {
        return false;
    }
}

Answer 5

Answer №3

if(!$('#select-box').find("option:contains('" + thevalue  + "')").length){
//execute code block
}

Answer 6

if(!$('#select-box').find("option:contains('" + thevalue  + "')").length){
//execute code block
}

Answer 7

Answer №4

When loading values from post parameters, I found success with this approach: if a value is missing from the select dropdown, an alert is shown to notify the user; otherwise, proceed as normal:

let selectElement = document.getElementById('your_select_id');
selectElement.value = target_value;
if (selectElement.value !== target_value) {
    alert('The selected value is not available in the dropdown');
    return;
}

Answer 8

When loading values from post parameters, I found success with this approach: if a value is missing from the select dropdown, an alert is shown to notify the user; otherwise, proceed as normal:

let selectElement = document.getElementById('your_select_id');
selectElement.value = target_value;
if (selectElement.value !== target_value) {
    alert('The selected value is not available in the dropdown');
    return;
}

Answer 9

Answer №5

accomplishing this task is possible using jquery

Utilize the Attribute Equals Selector

refer to

Verify value existence in select list with JQuery

implementing it in javascript can be done as follows

 for (var i=0; i<document.getElementById('mySelect').options.length; i++)
           { 
            if (document.getElementById('mySelect').options[i].text == seachtext) 
            { 
             alert('found');
             break;
            } 
       }

Answer 10

accomplishing this task is possible using jquery

Utilize the Attribute Equals Selector

refer to

Verify value existence in select list with JQuery

implementing it in javascript can be done as follows

 for (var i=0; i<document.getElementById('mySelect').options.length; i++)
           { 
            if (document.getElementById('mySelect').options[i].text == seachtext) 
            { 
             alert('found');
             break;
            } 
       }

Answer 11

Answer №6

According to @Haim Evgi:
To filter the `select.options` as an array, you can use this method:

Array.from(nSelect.options).filter(nOption => /*true or false)*/

If the filtered array still has options after the filtering process, it means a match has been found so the length should be > 0.

Below is a code snippet demonstrating how to search for value or text within the options:
The first checkbox is for searching by value, while the second one is for searching by innerText.

function selectContainsOption(nSelect, nValue, nCheckValue, nCheckText){ // HTMLElement, ~String, ~boolean, ~boolean
    nValue = (nValue == null ? "" : nValue);
    nCheckValue = (nCheckValue == null ? true : nCheckValue);
    nCheckText = (nCheckText == null ? false : nCheckText);
    // get options as array, filter the array and check if there is any option left
    return (
        Array.from(nSelect.options).filter(
            nOption => (nCheckValue && nOption.value == nValue) || (nCheckText && nOption.innerText == nValue)
        ).length > 0
    );
}

<select>
    <option value="1">Number 1</option>
    <option value="2">Number 2</option>
    <option value="3">Number 3</option>
    <option value="4">Number 4</option>
    <option value="5">Number 5</option>
    <option value="6">Number 6</option>
    <option value="7">Number 7</option>
    <option value="8">Number 8</option>
    <option value="9">Number 9</option>
    <option value="a">Character a</option>
    <option value="b">Character b</option>
    <option value="c">Character c</option>
    <option value="d">Character d</option>
    <option value="e">Character e</option>
    <option value="f">Character f</option>
</select>
<b> search: </b>
<input type="text" value="0" onchange="this.nextElementSibling.nextElementSibling.nextElementSibling.nextElementSibling.innerText = selectContainsOption(this.previousElementSibling.previousElementSibling, this.value, this.nextElementSibling.checked, this.nextElementSibling.nextElementSibling.checked);"/>
<input type="checkbox" checked="checked" onchange="this.previousElementSibling.onchange()"/>
<input type="checkbox" checked="checked" onchange="this.previousElementSibling.previousElementSibling.onchange()"/>
<b> contains: </b>
<span>false</span>

Answer 12

According to @Haim Evgi:
To filter the `select.options` as an array, you can use this method:

Array.from(nSelect.options).filter(nOption => /*true or false)*/

If the filtered array still has options after the filtering process, it means a match has been found so the length should be > 0.

Below is a code snippet demonstrating how to search for value or text within the options:
The first checkbox is for searching by value, while the second one is for searching by innerText.

function selectContainsOption(nSelect, nValue, nCheckValue, nCheckText){ // HTMLElement, ~String, ~boolean, ~boolean
    nValue = (nValue == null ? "" : nValue);
    nCheckValue = (nCheckValue == null ? true : nCheckValue);
    nCheckText = (nCheckText == null ? false : nCheckText);
    // get options as array, filter the array and check if there is any option left
    return (
        Array.from(nSelect.options).filter(
            nOption => (nCheckValue && nOption.value == nValue) || (nCheckText && nOption.innerText == nValue)
        ).length > 0
    );
}

<select>
    <option value="1">Number 1</option>
    <option value="2">Number 2</option>
    <option value="3">Number 3</option>
    <option value="4">Number 4</option>
    <option value="5">Number 5</option>
    <option value="6">Number 6</option>
    <option value="7">Number 7</option>
    <option value="8">Number 8</option>
    <option value="9">Number 9</option>
    <option value="a">Character a</option>
    <option value="b">Character b</option>
    <option value="c">Character c</option>
    <option value="d">Character d</option>
    <option value="e">Character e</option>
    <option value="f">Character f</option>
</select>
<b> search: </b>
<input type="text" value="0" onchange="this.nextElementSibling.nextElementSibling.nextElementSibling.nextElementSibling.innerText = selectContainsOption(this.previousElementSibling.previousElementSibling, this.value, this.nextElementSibling.checked, this.nextElementSibling.nextElementSibling.checked);"/>
<input type="checkbox" checked="checked" onchange="this.previousElementSibling.onchange()"/>
<input type="checkbox" checked="checked" onchange="this.previousElementSibling.previousElementSibling.onchange()"/>
<b> contains: </b>
<span>false</span>

Tips for verifying the presence of a value in a select box

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

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