this chapter we’ll cover selection in the document, as well as selection in form fields, such as <input… Selection in form controls.Form elements, such as input and textarea provide special API for selection… As an input value is a pure text, not HTML, there’s no need for such objects, everything’s much simpler… Methods:
input.select() – selects everything in the text control (can be textarea instead of input)… For input, textarea: additional methods and properties.
For text inputs that means that the event occurs when it loses focus.… On the other hand, input event doesn’t trigger on keyboard input and other actions that do not involve… value change, e.g. pressing arrow keys ⇦ ⇨ while in the input.… Can’t prevent anything in oninput
The input event occurs after the value is modified.… For text inputs triggers on focus loss.
input
For text inputs on every change.
Such as <input type="range">:
The browser uses DOM/CSS internally to draw them.… Then <input type="range"> looks like this:
What you see under #shadow-root… Browser-native shadow trees, such as <input type="range">, are closed.
We can put any type in a variable.… type can store larger integers (up to 1.7976931348623157 * 10308), but outside of the safe integer range… For most purposes ±(253-1) range is quite enough, but sometimes we need the entire range of really big… We can put anything in there: a variable like name or an arithmetical expression like 1 + 2 or something… To put it clear: typeof is an operator, not a function.
Supports key range queries, indexes.
Can store much bigger volumes of data than localStorage.… In our “books” storage that would be a value or range of values of book.id.… that specify an acceptable “key range”.… If the open flags is true, the corresponding key is not included in the range.… IDBKeyRange.only(key) – a range that consists of only one key, rarely used.
The range: {3,5}, match 3-5 times
To find numbers from 3 to 5 digits we can put the limits into curly
We can set out-of-range values, and it will auto-adjust itself.… Out-of-range… So it’s faster and doesn’t put pressure on garbage collection.… Date auto-corrects itself when out-of-range components are set.
A Bezier curve can make the animation exceed its range.… Then the Bezier curve would also extend very low or high, making the animation go beyond its normal range… The y is out of the “standard” range 0..1.… If we put y values like -99 and 99 then the train would jump out of the range much more.
Ranges.Square brackets may also contain character ranges.… For instance, [a-z] is a character in range from a to z, and [0-5] is a digit from 0 to 5.… If we’d like to look for lowercase letters as well, we can add the range a-f: [0-9A-Fa-f].… Or just use ranges of characters in a language that interests us, e.g.… Excluding ranges.Besides normal ranges, there are “excluding” ranges that look like [^…].
Move the mouse over the input field to see clientX/clientY (the example is in the iframe, so coordinates… There are multiple ways to prevent the selection, that you can read in the chapter Selection and Range
URL-path, we can set the option:
We can put… default if we set a header If-Modified-Since, If-None-Match, If-Unmodified-Since, If-Match, or If-Range… We can put it in the integrity option, like this:
Pointer events are a modern way to handle input from a variety of pointing devices, such as a mouse,… Where unsupported, it’s always 1.
pressure – the pressure of the pointer tip, in range from 0 to 1.… Here’s what happens when a user touches a touchscreen in one place, then puts another finger somewhere
Elastic animation.One more “elastic” function that accepts an additional parameter x for the “initial range… That’s done with the “easeOut” transform.
easeOut.In the “easeOut” mode the timing function is put into
For instance, let’s try to put 256 into Uint8Array.… 256 is 100000000 (9 bits), but Uint8Array only provides 8 bits per value, that makes the available range
To make the range object iterable (and thus let for..of work) we need to add a method… The range itself does not have the next() method.… Technically, we may merge them and use range itself as the iterator to make the code simpler.… For instance, the range becomes infinite for range.to = Infinity.… E.g. we would like to work with range using array methods. How to achieve that?
The idea is that we have an object, such as range here:… …And we’d like to use for..of loop on it, such as for(value of range), to get values… As a starting example, let’s make an iterable range object, similar like the one before, but now it will… To iterate, we use for await(let value of range) (4), namely add “await” after “for”.… It calls range[Symbol.asyncIterator]() once, and then its next() for values.
syntax)
Using generators for iterables.Some time ago, in the chapter Iterables we created an iterable range… Here’s the same range, but much more compact:… That works, because range… The variant with a generator is much more concise than the original iterable code of range, and keeps
That range is not big enough to encode all possible characters, that’s why some rare characters are encoded… We’ll see that a bit later, in the article Sets and ranges [...].
Event: submit.There are two main ways to submit a form:
The first – to click <input type="submit… "> or <input type="image">.… The second – press Enter on an input field.
Both actions lead to submit event on the form.… Click <input type="submit">.… field, a click event triggers on the <input type="submit">.
It shows a modal window with a text message, an input… title
The text to show the visitor.
default
An optional second parameter, the initial value for the input… The visitor can type something in the prompt input field and press OK.… Or they can cancel the input by pressing Cancel or hitting the Esc key, then we get null as the result… The call to prompt returns the text from the input field or null if the input was canceled.
Let’s use them for validation of an input field.… Modern HTML allows us to do many validations using input… If we enter something into the input and then try to use Tab or click away from the <input>, then… To make an element a part of the form on par with <input>.… >, the focus event triggers on that input only.
So if we want to track any input into an <input> field, then keyboard events are not enough.… There’s another event named input to track changes of an <input> field, by any means.… We’ll cover it later in the chapter Events: change, input, cut, copy, paste.… That’s not reliable, because the input can come from various sources.… We have input and change events to handle any input (covered later in the chapter Events: change, input
Second, more often we get a file from <input type="file"> or drag’n’drop or other browser… That’s how we can get a File object from <input type="file">:… Please note:
The input… We usually get File objects from user input, like <input> or Drag’n’Drop events (ondragend).
with the given name and value,
formData.append(name, blob, fileName) – add a field as if it were <input… So, <input type="file"> fields are sent also, similar to a usual form submission.… That’s same as if there were <input… syntax is needed, the last argument is a file name, that normally is taken from user filesystem for <input
For instance, mousedown on an <input> field leads to focusing in it, and the focus event.… Try to click on the first <input> below – the focus event happens.… The focusing is still possible if we use another way to enter the input.… For instance, the Tab key to switch from the 1st input into the 2nd.… type="checkbox"> – checks/unchecks the input.
submit – clicking an <input type="
returns the first match as an array with capturing groups and properties index (position of the match), input… (input string, equals str):… The function is called with arguments func(match, p1, p2, ..., pn, offset, input, groups):
match – the… p1, p2, ..., pn – contents of capturing groups (if there are any),
offset – position of the match,
input… If there are no parentheses in the regexp, then there are only 3 arguments: func(str, offset, input).
regexp like [\s\S] to match “any character” (this pattern will be covered in the article Sets and ranges
learn functions (a way to group commands), so let’s note in advance that "use strict" can be put… First, you can try to press Shift+Enter to input multiple lines, and put use strict on top, like this… Put it inside this kind of wrapper:
node corresponding to tag <a> has link-related properties, and the one corresponding to <input… > has input-related properties and so on.… It is inherited by concrete HTML elements:
HTMLInputElement – the class for <input> elements,… For example, let’s consider the DOM object for an <input> element.… And if there was an <input> with a text entered by the visitor, then the text will be removed.
For example, we can put there a table row <tr>:… Usually, if we try to put <tr> inside, say, a <div>, the browser detects the… We can put styles and scripts into <template> as well:
For instance, to check if the user input is in the right format.
We need to put a semicolon after alert for the code to work correctly.… We recommend putting semicolons between statements even if they are separated by newlines.… Comments can be put into any place of a script.… The content of comments is ignored, so if we put
Keyboard input is much difficult to redirect.… So when a visitor tries to focus on the input they see on the page, they actually focus on the input
Multi-line input
Usually, when we put a line of code into the console, and then press Enter
“In range” with “has” trap.Let’s see more examples.… We have a range object:
We’d like to… use the in operator to check that a number is in range.
Or, to put it more simply, when a promise is ready, its .then/catch/finally handlers are put into the… Easy, just put it into the queue with .then:
Forms and control elements, such as <input> have a lot of special properties and events.… Form elements.Let’s talk about form controls.
input
The break directive is activated at the line (*) if the user enters an empty line or cancels the input… We need a way to stop the process if the user cancels the input… The ordinary break after input would only break the inner loop.
*$ in the string An input that hangs!.… if we omit the space, becomes (\w+)*, leading to many combinations of \w+ within a single word
So input… The input string can’t be matched as two repetitions of \w+\s, because the space is mandatory.… We can put a more complex regular expression into (?
For instance:
Let’s find all input… That won’t work, because it takes a collection of inputs
The code design where a function gets “input” variables and produces certain “outcome” is clearer, less
Export apart from declarations.Also, we can put… export:
…Or, technically we could put… Import *.Usually, we put a list of what to import in curly braces import {...}, like this:… Put export default before the entity to export:… code runs), but do not assign any of its exports to variables:
import "module"
We can put
the visitor submits a <form>.
focus – when the visitor focuses on an element, e.g. on an <input… For instance, to assign a click handler for an input, we can use onclick, like here:… When an event happens, the browser creates an event object, puts details into it and passes it as an
If we put these operations on separate lines, then this will be lost for sure:… Here hi = user.hi puts
If we put a quantifier after the parentheses, it applies to the parentheses as a whole.… match without flag g: it’s an array with additional properties index (match index in the string) and input… That’s done by putting ?<name> immediately after the opening paren.
lot of elements handled in a similar way, then instead of assigning a handler to each of them – we put… Just make a method and put it in the markup.… The algorithm:
Put a single handler on the container.
External scripts.If we have a lot of JavaScript code, we can put it into a separate file.… Please note:
As a rule, only the simplest scripts are put
In other words, an empty "sandbox" attribute puts the strictest limitations possible, but we… can put a space-delimited list of those that we want to lift.… Then setting document.domain='site.com' in both of them puts them into the “same origin” state.… If an iframe has a sandbox attribute, it is forcefully put into the “different origin” state, unless
focusout,
click, dblclick,
mousedown, mouseup mousemove, mouseout, mouseover,
wheel,
beforeinput, input
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