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Uncaught TypeError: document.getElementById(...).value.totoUpperCase is not a function [duplicate]

I am working on a search with JavaScript. I would use a form, but it messes up something else on my page. I have this input text field:
<input name="searchTxt" type="text" maxlength="512" id="searchTxt" class="searchField"/>
And this is my JavaScript code:
<script type="text/javascript">
function searchURL(){
window.location = "http://www.myurl.com/search/" + (input text value);
}
</script>
How do I get the value from the text field into JavaScript?

There are various methods to get an input textbox value directly (without wrapping the input element inside a form element):
Method 1
document.getElementById('textbox_id').value to get the value of
desired box
For example
document.getElementById("searchTxt").value;
 
Note: Method 2,3,4 and 6 returns a collection of elements, so use [whole_number] to get the desired occurrence. For the first element, use [0],
for the second one use [1], and so on...
Method 2
Use
document.getElementsByClassName('class_name')[whole_number].value which returns a Live HTMLCollection
For example
document.getElementsByClassName("searchField")[0].value; if this is the first textbox in your page.
Method 3
Use document.getElementsByTagName('tag_name')[whole_number].value which also returns a live HTMLCollection
For example
document.getElementsByTagName("input")[0].value;, if this is the first textbox in your page.
Method 4
document.getElementsByName('name')[whole_number].value which also >returns a live NodeList
For example
document.getElementsByName("searchTxt")[0].value; if this is the first textbox with name 'searchtext' in your page.
Method 5
Use the powerful document.querySelector('selector').value which uses a CSS selector to select the element
For example
document.querySelector('#searchTxt').value; selected by id
document.querySelector('.searchField').value; selected by class
document.querySelector('input').value; selected by tagname
document.querySelector('[name="searchTxt"]').value; selected by name
Method 6
document.querySelectorAll('selector')[whole_number].value which also uses a CSS selector to select elements, but it returns all elements with that selector as a static Nodelist.
For example
document.querySelectorAll('#searchTxt')[0].value; selected by id
document.querySelectorAll('.searchField')[0].value; selected by class
document.querySelectorAll('input')[0].value; selected by tagname
document.querySelectorAll('[name="searchTxt"]')[0].value; selected by name
Support
Browser
Method1
Method2
Method3
Method4
Method5/6
IE6
Y(Buggy)
N
Y
Y(Buggy)
N
IE7
Y(Buggy)
N
Y
Y(Buggy)
N
IE8
Y
N
Y
Y(Buggy)
Y
IE9
Y
Y
Y
Y(Buggy)
Y
IE10
Y
Y
Y
Y
Y
FF3.0
Y
Y
Y
Y
N IE=Internet Explorer
FF3.5/FF3.6
Y
Y
Y
Y
Y FF=Mozilla Firefox
FF4b1
Y
Y
Y
Y
Y GC=Google Chrome
GC4/GC5
Y
Y
Y
Y
Y Y=YES,N=NO
Safari4/Safari5
Y
Y
Y
Y
Y
Opera10.10/
Opera10.53/
Y
Y
Y
Y(Buggy)
Y
Opera10.60
Opera 12
Y
Y
Y
Y
Y
Useful links
To see the support of these methods with all the bugs including more details click here
Difference Between Static collections and Live collections click Here
Difference Between NodeList and HTMLCollection click Here

//creates a listener for when you press a key
window.onkeyup = keyup;
//creates a global Javascript variable
var inputTextValue;
function keyup(e) {
//setting your input text to the global Javascript Variable for every key press
inputTextValue = e.target.value;
//listens for you to press the ENTER key, at which point your web address will change to the one you have input in the search box
if (e.keyCode == 13) {
window.location = "http://www.myurl.com/search/" + inputTextValue;
}
}
See this functioning in codepen.

I would create a variable to store the input like this:
var input = document.getElementById("input_id").value;
And then I would just use the variable to add the input value to the string.
= "Your string" + input;

You should be able to type:
var input = document.getElementById("searchTxt");
function searchURL() {
window.location = "http://www.myurl.com/search/" + input.value;
}
<input name="searchTxt" type="text" maxlength="512" id="searchTxt" class="searchField"/>
I'm sure there are better ways to do this, but this one seems to work across all browsers, and it requires minimal understanding of JavaScript to make, improve, and edit.

Also you can, call by tags names, like this: form_name.input_name.value;
So you will have the specific value of determined input in a specific form.

Short
You can read value by searchTxt.value
<input name="searchTxt" type="text" maxlength="512" id="searchTxt" class="searchField"/>
<script type="text/javascript">
function searchURL(){
console.log(searchTxt.value);
// window.location = "http://www.myurl.com/search/" + searchTxt.value;
}
</script>
<!-- SHORT ugly test code -->
<button class="search" onclick="searchURL()">Search</button>

<input type="text" onkeyup="trackChange(this.value)" id="myInput">
<script>
function trackChange(value) {
window.open("http://www.google.com/search?output=search&q=" + value)
}
</script>

Tested in Chrome and Firefox:
Get value by element id:
<input type="text" maxlength="512" id="searchTxt" class="searchField"/>
<input type="button" value="Get Value" onclick="alert(searchTxt.value)">
Set value in form element:
<form name="calc" id="calculator">
<input type="text" name="input">
<input type="button" value="Set Value" onclick="calc.input.value='Set Value'">
</form>
https://jsfiddle.net/tuq79821/
Also have a look at a JavaScript calculator implementation.
From #bugwheels94: when using this method, be aware of this issue.

If your input is in a form and you want to get the value after submit you can do like:
<form onsubmit="submitLoginForm(event)">
<input type="text" name="name">
<input type="password" name="password">
<input type="submit" value="Login">
</form>
<script type="text/javascript">
function submitLoginForm(event){
event.preventDefault();
console.log(event.target['name'].value);
console.log(event.target['password'].value);
}
</script>
Benefit of this way: Example your page have 2 form for input sender and receiver information.
If you don't use form for get value then
You can set two different id (or tag or name ...) for each field like sender-name and receiver-name, sender-address and receiver-address, ...
If you set the same value for two inputs, then after getElementsByName (or getElementsByTagName ...) you need to remember 0 or 1 is sender or receiver. Later, if you change the order of 2 form in HTML, you need to check this code again
If you use form, then you can use name, address, ...

You can use onkeyup when you have more than one input field. Suppose you have four or input. Then
document.getElementById('something').value is annoying. We need to write four lines to fetch the value of an input field.
So, you can create a function that store value in object on keyup or keydown event.
Example:
<div class="container">
<div>
<label for="">Name</label>
<input type="text" name="fname" id="fname" onkeyup=handleInput(this)>
</div>
<div>
<label for="">Age</label>
<input type="number" name="age" id="age" onkeyup=handleInput(this)>
</div>
<div>
<label for="">Email</label>
<input type="text" name="email" id="email" onkeyup=handleInput(this)>
</div>
<div>
<label for="">Mobile</label>
<input type="number" name="mobile" id="number" onkeyup=handleInput(this)>
</div>
<div>
<button onclick=submitData()>Submit</button>
</div>
</div>
JavaScript:
<script>
const data = { };
function handleInput(e){
data[e.name] = e.value;
}
function submitData(){
console.log(data.fname); // Get the first name from the object
console.log(data); // return object
}
</script>

function handleValueChange() {
var y = document.getElementById('textbox_id').value;
var x = document.getElementById('result');
x.innerHTML = y;
}
function changeTextarea() {
var a = document.getElementById('text-area').value;
var b = document.getElementById('text-area-result');
b.innerHTML = a;
}
input {
padding: 5px;
}
p {
white-space: pre;
}
<input type="text" id="textbox_id" placeholder="Enter string here..." oninput="handleValueChange()">
<p id="result"></p>
<textarea name="" id="text-area" cols="20" rows="5" oninput="changeTextarea()"></textarea>
<p id="text-area-result"></p>

<input id="new" >
<button onselect="myFunction()">it</button>
<script>
function myFunction() {
document.getElementById("new").value = "a";
}
</script>

One can use the form.elements to get all elements in a form. If an element has id it can be found with .namedItem("id"). Example:
var myForm = document.getElementById("form1");
var text = myForm.elements.namedItem("searchTxt").value;
var url = "http://www.myurl.com/search/" + text;
Source: w3schools

function searchURL() {
window.location = 'http://www.myurl.com/search/' + searchTxt.value
}
So basically searchTxt.value will return the value of the input field with id='searchTxt'.

Short Answer
You can get the value of text input field using JavaScript with this code: input_text_value = console.log(document.getElementById("searchTxt").value)
More info
textObject has a property of value you can set and get this property.
To set you can assign a new value:
document.getElementById("searchTxt").value = "new value"

Simple JavaScript:
function copytext(text) {
var textField = document.createElement('textarea');
textField.innerText = text;
document.body.appendChild(textField);
textField.select();
document.execCommand('copy');
textField.remove();
}

Why is if block executing and not the else block in javascript? [duplicate]

I am working on a search with JavaScript. I would use a form, but it messes up something else on my page. I have this input text field:
<input name="searchTxt" type="text" maxlength="512" id="searchTxt" class="searchField"/>
And this is my JavaScript code:
<script type="text/javascript">
function searchURL(){
window.location = "http://www.myurl.com/search/" + (input text value);
}
</script>
How do I get the value from the text field into JavaScript?

There are various methods to get an input textbox value directly (without wrapping the input element inside a form element):
Method 1
document.getElementById('textbox_id').value to get the value of
desired box
For example
document.getElementById("searchTxt").value;
 
Note: Method 2,3,4 and 6 returns a collection of elements, so use [whole_number] to get the desired occurrence. For the first element, use [0],
for the second one use [1], and so on...
Method 2
Use
document.getElementsByClassName('class_name')[whole_number].value which returns a Live HTMLCollection
For example
document.getElementsByClassName("searchField")[0].value; if this is the first textbox in your page.
Method 3
Use document.getElementsByTagName('tag_name')[whole_number].value which also returns a live HTMLCollection
For example
document.getElementsByTagName("input")[0].value;, if this is the first textbox in your page.
Method 4
document.getElementsByName('name')[whole_number].value which also >returns a live NodeList
For example
document.getElementsByName("searchTxt")[0].value; if this is the first textbox with name 'searchtext' in your page.
Method 5
Use the powerful document.querySelector('selector').value which uses a CSS selector to select the element
For example
document.querySelector('#searchTxt').value; selected by id
document.querySelector('.searchField').value; selected by class
document.querySelector('input').value; selected by tagname
document.querySelector('[name="searchTxt"]').value; selected by name
Method 6
document.querySelectorAll('selector')[whole_number].value which also uses a CSS selector to select elements, but it returns all elements with that selector as a static Nodelist.
For example
document.querySelectorAll('#searchTxt')[0].value; selected by id
document.querySelectorAll('.searchField')[0].value; selected by class
document.querySelectorAll('input')[0].value; selected by tagname
document.querySelectorAll('[name="searchTxt"]')[0].value; selected by name
Support
Browser
Method1
Method2
Method3
Method4
Method5/6
IE6
Y(Buggy)
N
Y
Y(Buggy)
N
IE7
Y(Buggy)
N
Y
Y(Buggy)
N
IE8
Y
N
Y
Y(Buggy)
Y
IE9
Y
Y
Y
Y(Buggy)
Y
IE10
Y
Y
Y
Y
Y
FF3.0
Y
Y
Y
Y
N IE=Internet Explorer
FF3.5/FF3.6
Y
Y
Y
Y
Y FF=Mozilla Firefox
FF4b1
Y
Y
Y
Y
Y GC=Google Chrome
GC4/GC5
Y
Y
Y
Y
Y Y=YES,N=NO
Safari4/Safari5
Y
Y
Y
Y
Y
Opera10.10/
Opera10.53/
Y
Y
Y
Y(Buggy)
Y
Opera10.60
Opera 12
Y
Y
Y
Y
Y
Useful links
To see the support of these methods with all the bugs including more details click here
Difference Between Static collections and Live collections click Here
Difference Between NodeList and HTMLCollection click Here

//creates a listener for when you press a key
window.onkeyup = keyup;
//creates a global Javascript variable
var inputTextValue;
function keyup(e) {
//setting your input text to the global Javascript Variable for every key press
inputTextValue = e.target.value;
//listens for you to press the ENTER key, at which point your web address will change to the one you have input in the search box
if (e.keyCode == 13) {
window.location = "http://www.myurl.com/search/" + inputTextValue;
}
}
See this functioning in codepen.

I would create a variable to store the input like this:
var input = document.getElementById("input_id").value;
And then I would just use the variable to add the input value to the string.
= "Your string" + input;

You should be able to type:
var input = document.getElementById("searchTxt");
function searchURL() {
window.location = "http://www.myurl.com/search/" + input.value;
}
<input name="searchTxt" type="text" maxlength="512" id="searchTxt" class="searchField"/>
I'm sure there are better ways to do this, but this one seems to work across all browsers, and it requires minimal understanding of JavaScript to make, improve, and edit.

Also you can, call by tags names, like this: form_name.input_name.value;
So you will have the specific value of determined input in a specific form.

Short
You can read value by searchTxt.value
<input name="searchTxt" type="text" maxlength="512" id="searchTxt" class="searchField"/>
<script type="text/javascript">
function searchURL(){
console.log(searchTxt.value);
// window.location = "http://www.myurl.com/search/" + searchTxt.value;
}
</script>
<!-- SHORT ugly test code -->
<button class="search" onclick="searchURL()">Search</button>

<input type="text" onkeyup="trackChange(this.value)" id="myInput">
<script>
function trackChange(value) {
window.open("http://www.google.com/search?output=search&q=" + value)
}
</script>

Tested in Chrome and Firefox:
Get value by element id:
<input type="text" maxlength="512" id="searchTxt" class="searchField"/>
<input type="button" value="Get Value" onclick="alert(searchTxt.value)">
Set value in form element:
<form name="calc" id="calculator">
<input type="text" name="input">
<input type="button" value="Set Value" onclick="calc.input.value='Set Value'">
</form>
https://jsfiddle.net/tuq79821/
Also have a look at a JavaScript calculator implementation.
From #bugwheels94: when using this method, be aware of this issue.

If your input is in a form and you want to get the value after submit you can do like:
<form onsubmit="submitLoginForm(event)">
<input type="text" name="name">
<input type="password" name="password">
<input type="submit" value="Login">
</form>
<script type="text/javascript">
function submitLoginForm(event){
event.preventDefault();
console.log(event.target['name'].value);
console.log(event.target['password'].value);
}
</script>
Benefit of this way: Example your page have 2 form for input sender and receiver information.
If you don't use form for get value then
You can set two different id (or tag or name ...) for each field like sender-name and receiver-name, sender-address and receiver-address, ...
If you set the same value for two inputs, then after getElementsByName (or getElementsByTagName ...) you need to remember 0 or 1 is sender or receiver. Later, if you change the order of 2 form in HTML, you need to check this code again
If you use form, then you can use name, address, ...

You can use onkeyup when you have more than one input field. Suppose you have four or input. Then
document.getElementById('something').value is annoying. We need to write four lines to fetch the value of an input field.
So, you can create a function that store value in object on keyup or keydown event.
Example:
<div class="container">
<div>
<label for="">Name</label>
<input type="text" name="fname" id="fname" onkeyup=handleInput(this)>
</div>
<div>
<label for="">Age</label>
<input type="number" name="age" id="age" onkeyup=handleInput(this)>
</div>
<div>
<label for="">Email</label>
<input type="text" name="email" id="email" onkeyup=handleInput(this)>
</div>
<div>
<label for="">Mobile</label>
<input type="number" name="mobile" id="number" onkeyup=handleInput(this)>
</div>
<div>
<button onclick=submitData()>Submit</button>
</div>
</div>
JavaScript:
<script>
const data = { };
function handleInput(e){
data[e.name] = e.value;
}
function submitData(){
console.log(data.fname); // Get the first name from the object
console.log(data); // return object
}
</script>

function handleValueChange() {
var y = document.getElementById('textbox_id').value;
var x = document.getElementById('result');
x.innerHTML = y;
}
function changeTextarea() {
var a = document.getElementById('text-area').value;
var b = document.getElementById('text-area-result');
b.innerHTML = a;
}
input {
padding: 5px;
}
p {
white-space: pre;
}
<input type="text" id="textbox_id" placeholder="Enter string here..." oninput="handleValueChange()">
<p id="result"></p>
<textarea name="" id="text-area" cols="20" rows="5" oninput="changeTextarea()"></textarea>
<p id="text-area-result"></p>

<input id="new" >
<button onselect="myFunction()">it</button>
<script>
function myFunction() {
document.getElementById("new").value = "a";
}
</script>

One can use the form.elements to get all elements in a form. If an element has id it can be found with .namedItem("id"). Example:
var myForm = document.getElementById("form1");
var text = myForm.elements.namedItem("searchTxt").value;
var url = "http://www.myurl.com/search/" + text;
Source: w3schools

function searchURL() {
window.location = 'http://www.myurl.com/search/' + searchTxt.value
}
So basically searchTxt.value will return the value of the input field with id='searchTxt'.

Short Answer
You can get the value of text input field using JavaScript with this code: input_text_value = console.log(document.getElementById("searchTxt").value)
More info
textObject has a property of value you can set and get this property.
To set you can assign a new value:
document.getElementById("searchTxt").value = "new value"

Simple JavaScript:
function copytext(text) {
var textField = document.createElement('textarea');
textField.innerText = text;
document.body.appendChild(textField);
textField.select();
document.execCommand('copy');
textField.remove();
}

HTML FORM - Change Parts Of Readonly String Field Using onchange()

I want to assign the values - value and value 2 into the DATAID and DEPNUM when clicking the drop-down and using onchange() function in the following HTML FORM
The places that are being assigned are parts of a readonly field which contains string.
My goal is to create a readonly string which will contain the values that I've chosen from the dropdown fields, all combined in 1 string and separated by underscore.
I've been trying to use onChange method "myFunction()"
<input name="_1_1_2_1" tabindex="-1" class="valueEditable" id="myInput" onchange="myFunction()" type="text" size="32" value="...">
which will look like :
function myFunction()
{
var x = document.getElementById("myInput").value;
document.getElementById("demo").innerHTML = x;
}
eventually I run it on the paragraph :
<p id="demo" value="DATAID_DOCTYPE_DEPNUM_NTA">DATAID_DOCTYPE_DEPNUM_NTA</p>
The problem is that the value at is not changing instant as i change value2 or value.

You can bind two event-listener for both two input fields and updated the readonly textfield value by below approach.
$(document).ready(function(){
$('#field1').keyup(function() {
updatedReadonlyFieldVal($(this), 0);
});
$('#field2').keyup(function() {
updatedReadonlyFieldVal($(this), 2);
});
function updatedReadonlyFieldVal(elem, index) {
let val = elem.val();
let destVal = $('#destination').val();
let splittedDestVal = destVal.split('_');
splittedDestVal[index] = val;
$('#destination').val(splittedDestVal.join('_'));
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="text" id="field1" name="field1">
<input type="text" id="field2" name="field2">
<input value="DATAID_DOCTYPE_DATANUM" readonly id="destination">
Please don't hesitate to let me know if you have any query.

Restore textfield's default value when user clicks the reset button JavaScript

I'm trying to get the textfields to return to their default value when the user clicks the Reset button.
All it does now when the user clicks the Reset button is replacing the user's text with ''.
How can I do it by using pure JavaScript (no jQuery)?
HTML:
<p>Type the first number</p>
<input id="first" type="text" placeholder="First Number" />
<p>Type the second number</p>
<input id="second" type="text" placeholder="Second Number" />
<button id="aButton">Apply</button>
<button id="rButton">Reset</button>
<div id="add"></div>
JAVASCRIPT:
app.onactivated = function (args) {
var aButton = document.getElementById("aButton");
aButton.addEventListener("click", buttonClickHandler, false);
var rButton = document.getElementById("rButton");
rButton.addEventListener("click", buttonResetHandler, false);
};
...
function buttonResetHandler(evetInfo) {
document.getElementById("first").innerText = '';
document.getElementById("second").innerText = '';
}

innerText is an invalid property that is implemented in IE browsers and is used for setting/getting text content of non-form elements, if the values should be set as default, you can use defaultValue property:
var a = document.getElementById("first"),
b = document.getElementById("second");
a.value = a.defaultValue;
b.value = b.defaultValue;
If you want to reset all the form elements, you can use .reset() method of DOM HTMLFormElement object:
document.forms["myForm"].reset();

location.reload(); // reloads the page
history.go(0); // deletes the history
But if you need to preserve some values inside of the page then reassign the values in the function again. To reassign, write the variable (declare in let to change later) again in the function and change the textContent again.

Replace,
document.getElementById("first").innerText
With,
document.getElementById("first").value
Example:
<input id="txtBox" type="text" value="lama">
<input type="button" value="reset lama" onclick='document.getElementById("txtBox").value="lama2";'>

create an init function that sets the default values for each input, then you can call that:
function initializeInputs() {
document.getElementById("first").value = '';
document.getElementById("second").value= '';
}
function buttonResetHandler(e) {
initializeInputs();
}

How do I get the value of text input field using JavaScript?

I am working on a search with JavaScript. I would use a form, but it messes up something else on my page. I have this input text field:
<input name="searchTxt" type="text" maxlength="512" id="searchTxt" class="searchField"/>
And this is my JavaScript code:
<script type="text/javascript">
function searchURL(){
window.location = "http://www.myurl.com/search/" + (input text value);
}
</script>
How do I get the value from the text field into JavaScript?

There are various methods to get an input textbox value directly (without wrapping the input element inside a form element):
Method 1
document.getElementById('textbox_id').value to get the value of
desired box
For example
document.getElementById("searchTxt").value;
 
Note: Method 2,3,4 and 6 returns a collection of elements, so use [whole_number] to get the desired occurrence. For the first element, use [0],
for the second one use [1], and so on...
Method 2
Use
document.getElementsByClassName('class_name')[whole_number].value which returns a Live HTMLCollection
For example
document.getElementsByClassName("searchField")[0].value; if this is the first textbox in your page.
Method 3
Use document.getElementsByTagName('tag_name')[whole_number].value which also returns a live HTMLCollection
For example
document.getElementsByTagName("input")[0].value;, if this is the first textbox in your page.
Method 4
document.getElementsByName('name')[whole_number].value which also >returns a live NodeList
For example
document.getElementsByName("searchTxt")[0].value; if this is the first textbox with name 'searchtext' in your page.
Method 5
Use the powerful document.querySelector('selector').value which uses a CSS selector to select the element
For example
document.querySelector('#searchTxt').value; selected by id
document.querySelector('.searchField').value; selected by class
document.querySelector('input').value; selected by tagname
document.querySelector('[name="searchTxt"]').value; selected by name
Method 6
document.querySelectorAll('selector')[whole_number].value which also uses a CSS selector to select elements, but it returns all elements with that selector as a static Nodelist.
For example
document.querySelectorAll('#searchTxt')[0].value; selected by id
document.querySelectorAll('.searchField')[0].value; selected by class
document.querySelectorAll('input')[0].value; selected by tagname
document.querySelectorAll('[name="searchTxt"]')[0].value; selected by name
Support
Browser
Method1
Method2
Method3
Method4
Method5/6
IE6
Y(Buggy)
N
Y
Y(Buggy)
N
IE7
Y(Buggy)
N
Y
Y(Buggy)
N
IE8
Y
N
Y
Y(Buggy)
Y
IE9
Y
Y
Y
Y(Buggy)
Y
IE10
Y
Y
Y
Y
Y
FF3.0
Y
Y
Y
Y
N IE=Internet Explorer
FF3.5/FF3.6
Y
Y
Y
Y
Y FF=Mozilla Firefox
FF4b1
Y
Y
Y
Y
Y GC=Google Chrome
GC4/GC5
Y
Y
Y
Y
Y Y=YES,N=NO
Safari4/Safari5
Y
Y
Y
Y
Y
Opera10.10/
Opera10.53/
Y
Y
Y
Y(Buggy)
Y
Opera10.60
Opera 12
Y
Y
Y
Y
Y
Useful links
To see the support of these methods with all the bugs including more details click here
Difference Between Static collections and Live collections click Here
Difference Between NodeList and HTMLCollection click Here

//creates a listener for when you press a key
window.onkeyup = keyup;
//creates a global Javascript variable
var inputTextValue;
function keyup(e) {
//setting your input text to the global Javascript Variable for every key press
inputTextValue = e.target.value;
//listens for you to press the ENTER key, at which point your web address will change to the one you have input in the search box
if (e.keyCode == 13) {
window.location = "http://www.myurl.com/search/" + inputTextValue;
}
}
See this functioning in codepen.

I would create a variable to store the input like this:
var input = document.getElementById("input_id").value;
And then I would just use the variable to add the input value to the string.
= "Your string" + input;

You should be able to type:
var input = document.getElementById("searchTxt");
function searchURL() {
window.location = "http://www.myurl.com/search/" + input.value;
}
<input name="searchTxt" type="text" maxlength="512" id="searchTxt" class="searchField"/>
I'm sure there are better ways to do this, but this one seems to work across all browsers, and it requires minimal understanding of JavaScript to make, improve, and edit.

Also you can, call by tags names, like this: form_name.input_name.value;
So you will have the specific value of determined input in a specific form.

Short
You can read value by searchTxt.value
<input name="searchTxt" type="text" maxlength="512" id="searchTxt" class="searchField"/>
<script type="text/javascript">
function searchURL(){
console.log(searchTxt.value);
// window.location = "http://www.myurl.com/search/" + searchTxt.value;
}
</script>
<!-- SHORT ugly test code -->
<button class="search" onclick="searchURL()">Search</button>

<input type="text" onkeyup="trackChange(this.value)" id="myInput">
<script>
function trackChange(value) {
window.open("http://www.google.com/search?output=search&q=" + value)
}
</script>

Tested in Chrome and Firefox:
Get value by element id:
<input type="text" maxlength="512" id="searchTxt" class="searchField"/>
<input type="button" value="Get Value" onclick="alert(searchTxt.value)">
Set value in form element:
<form name="calc" id="calculator">
<input type="text" name="input">
<input type="button" value="Set Value" onclick="calc.input.value='Set Value'">
</form>
https://jsfiddle.net/tuq79821/
Also have a look at a JavaScript calculator implementation.
From #bugwheels94: when using this method, be aware of this issue.

If your input is in a form and you want to get the value after submit you can do like:
<form onsubmit="submitLoginForm(event)">
<input type="text" name="name">
<input type="password" name="password">
<input type="submit" value="Login">
</form>
<script type="text/javascript">
function submitLoginForm(event){
event.preventDefault();
console.log(event.target['name'].value);
console.log(event.target['password'].value);
}
</script>
Benefit of this way: Example your page have 2 form for input sender and receiver information.
If you don't use form for get value then
You can set two different id (or tag or name ...) for each field like sender-name and receiver-name, sender-address and receiver-address, ...
If you set the same value for two inputs, then after getElementsByName (or getElementsByTagName ...) you need to remember 0 or 1 is sender or receiver. Later, if you change the order of 2 form in HTML, you need to check this code again
If you use form, then you can use name, address, ...

You can use onkeyup when you have more than one input field. Suppose you have four or input. Then
document.getElementById('something').value is annoying. We need to write four lines to fetch the value of an input field.
So, you can create a function that store value in object on keyup or keydown event.
Example:
<div class="container">
<div>
<label for="">Name</label>
<input type="text" name="fname" id="fname" onkeyup=handleInput(this)>
</div>
<div>
<label for="">Age</label>
<input type="number" name="age" id="age" onkeyup=handleInput(this)>
</div>
<div>
<label for="">Email</label>
<input type="text" name="email" id="email" onkeyup=handleInput(this)>
</div>
<div>
<label for="">Mobile</label>
<input type="number" name="mobile" id="number" onkeyup=handleInput(this)>
</div>
<div>
<button onclick=submitData()>Submit</button>
</div>
</div>
JavaScript:
<script>
const data = { };
function handleInput(e){
data[e.name] = e.value;
}
function submitData(){
console.log(data.fname); // Get the first name from the object
console.log(data); // return object
}
</script>

function handleValueChange() {
var y = document.getElementById('textbox_id').value;
var x = document.getElementById('result');
x.innerHTML = y;
}
function changeTextarea() {
var a = document.getElementById('text-area').value;
var b = document.getElementById('text-area-result');
b.innerHTML = a;
}
input {
padding: 5px;
}
p {
white-space: pre;
}
<input type="text" id="textbox_id" placeholder="Enter string here..." oninput="handleValueChange()">
<p id="result"></p>
<textarea name="" id="text-area" cols="20" rows="5" oninput="changeTextarea()"></textarea>
<p id="text-area-result"></p>

<input id="new" >
<button onselect="myFunction()">it</button>
<script>
function myFunction() {
document.getElementById("new").value = "a";
}
</script>

One can use the form.elements to get all elements in a form. If an element has id it can be found with .namedItem("id"). Example:
var myForm = document.getElementById("form1");
var text = myForm.elements.namedItem("searchTxt").value;
var url = "http://www.myurl.com/search/" + text;
Source: w3schools

function searchURL() {
window.location = 'http://www.myurl.com/search/' + searchTxt.value
}
So basically searchTxt.value will return the value of the input field with id='searchTxt'.

Short Answer
You can get the value of text input field using JavaScript with this code: input_text_value = console.log(document.getElementById("searchTxt").value)
More info
textObject has a property of value you can set and get this property.
To set you can assign a new value:
document.getElementById("searchTxt").value = "new value"

Simple JavaScript:
function copytext(text) {
var textField = document.createElement('textarea');
textField.innerText = text;
document.body.appendChild(textField);
textField.select();
document.execCommand('copy');
textField.remove();
}