I pass my simple data from child to parent and I'm just wondering if I could omit to create a method for assigning this value to data? I would like to be able to assign it directly in the template.
My code is:
Child
<h1 #click="$emit('title', 'Home')" />
Parent
<div #title="onTitleChange" />
onTitleChange(newTitle) {
this.title = newTitle;
}
I would like to see something like this:
Child
<h1 #click="$emit('title', 'Home')" />
Parent
<div #title="title = value" />
You can access the emitted event’s value with $event. So, just a minor change in your parent.
<div #title="title = $event" />
Reference: https://v2.vuejs.org/v2/guide/components.html#Emitting-a-Value-With-an-Event
Related
Dears, I have tried to apply function to reverse string in paragraph text in vue.js,
I have created function to reverse words in methods called (reverseword) and added it card using :rule="reverseword()",but it does not work. your support is highly appreciated
Code:
<div class="post-box">
<span class="post-viwes">{{viwes}}</span>
<h3 class="post-title">{{title}}</h3>
<span class="post-date">{{date}}</span>
<p class="post-content">{{content}}</p>
<div class="row">
<div class = "col-sm-6 text-right">
<span class="post-author">{{author}} </span>
</div>
<div class = "col-sm-6 text-right" :rules="reverseword()">
<span class="post-category" >{{category.toUpperCase()}}</span>
</div>
</div>
)
</div>
</template>
<script>
export default {
props:["viwes","title","date","content","author","category"],
name:"posts",
methods: {
reverseWord: function () {
this.category = this.category.split('').reverse().join('')
}
}};
</script>```
Your reverseWord method attempts to mutate a prop (category).
You can't mutate a prop, because the mutation would be overwritten by the first update from the parent.
If/when you do want/need to change a prop value, you have do it in the parent component which will then pass the change down to the child component, through the props binding.
Updating the parent from child can be done by
either using $emit
or by using a store, external to both the child and the parent.
If, in fact, you don't want to mutate category, you just need to be able to use its reverse inside the template, create a computed property:
computed: {
reversedCategory() {
return this.category.split('').reverse().join('');
}
}
Use it in template as you would use a normal property:
<div class = "col-sm-6 text-right" :rules="reversedCategory">
<span class="post-category" >{{category.toUpperCase()}}</span>
</div>
The computed is reactive. Meaning every time category changes, reverseCategory will update accordingly.
So I´ve never used Template Literals before, but I need to work with a template now that seemingly includes a form with Template Literals
This is one of my inputs:
<input
type="number"
className="mf-input "
min="1900"
max="2099"
step="1"
id="curyear"
name="currentyear"
placeholder="${ parent.decodeEntities(`Current Year`) } "
onInput=${parent.handleChange}
aria-invalid=${validation.errors['currentyear'] ? 'true' : 'false'}
ref=${el => parent.activateValidation({"message":"This field is required.","minLength":1900,"maxLength":2099,"type":"by_character_length","required":false,"expression":"null"}, el)}
/>
<${validation.ErrorMessage}
errors=${validation.errors}
name="currentyear"
as=${html`<span className="mf-error-message"></span>`}
/>
What I am trying to do is, in the onInput method, instead of handling the validation, I also want to change the innerHTML of an element:
<h2 class="elementor-heading-title elementor-size-default" id="curyeartext">Current Year</h2>
I´ve been trying to do it for hours, but I can't get it to work.
EDIT: turns out, they are template literals and not reactJS
Avoid setting innerHTML inside React, use state instead. This is because React will overwrite your modified DOM when it re-renders, if the html is in a node that React is controlling.
export default function MyReactComponent() {
var [ currentInput, setCurrentInput ] = React.useState();
return <>
<input
type="number"
className="mf-input"
min="1900"
max="2099"
step="1"
name="currentyear"
onInput={(e) => setCurrentInput(e.target.value)}
value={currentInput}
/>
<h2 class="elementor-heading-title elementor-size-default" id="curyeartext">
{currentInput}
</h2>
</>;
}
However, if you have a situation where it is unavoidable, you can tell React to ignore a node by only specifying a ref on it - i.e. no other props or child JSX:
export default function MyReactComponent() {
return <div ref={divRef => {
divRef.innerHTML = "Hello <b>world!</b>";
}} />
}
This technique is typically used when integrating non-React specific JS libraries into React, as you can do whatever you want with the contents of that DOM node.
I managed to do this by adding a function above the return:
function myfunction() {
document.querySelector('#curyeartext').innerHTML = document.querySelector('#curyear').value;
document.querySelector('#lastyear').innerHTML = document.querySelector('#curyear').value-1;
document.querySelector('#yearbefore').innerHTML = document.querySelector('#curyear').value-2;
}
And call it in the onInput event handler
onInput=${myfunction}
I am new to Vue.js (I mostly use PHP) and I am trying to creating simple view where user can add an object from one component and place it's copy into another component.
Main template
<template>
<div class="left">
<TaskList :tasks="tasks" v-on:pinned-add-task="pinnedAddTask" />
</div>
<div class="right">
<PinnedList :pinned="pinned" />
</div>
</template>
TaskList
<template>
<div class="task-list">
<div v-for="task in tasks" :key="task.id">
<TaskItem :task="task" v-on:pinned-add-task="$emit('pinned-add-task', task)" />
</div>
</div>
</template>
TaskItem
<template>
<div>
<p>{{task.name}}</p>
<button v-on:click="$emit('pinned-add-task', task)">+</button>
</div>
</template>
And as far as I am aware object "task" is passed by reference and when I try to create an empty object or an array and insert "task" into that newly created object/array when I change original "task" it is also being changed inside that new object and I don't want that.
I am getting my data (tasks) from API that I have created and I am using pagination system so I want to be able to switch pages without losing it from the pinned page.
I created code which looks like this but I don't like it and I don't think that's a good way to do this:
pinnedAddTask(item) {
let pQuantity = 1; // I use this value because I want to be able to pin one task multipletimes
let left = this.pinned;
let right = [];
for (let task of this.pinned) {
if(item.id == task.id) {
pQuantity = task.quantity + 1;
left = this.pinned.filter(eItem => eItem.id < item.id);
right = this.pinned.filter(eItem => eItem.id > item.id);
}
}
const clone = {...item, quantity: pQuantity};
this.pinned = [...left, clone, ...right];
}
Can anyone confirm or reject this?
Yes this one is fine if thats just a shallow copy [ level-one object].
But if you are having a nested object then you might have to use recursive methodology or use any external libary like lodash
I want to pass a value from HTML page to child function from parent function.
HTML Page:
<div class="bottom_wrapper clearfix">
<div class="message_input_wrapper">
<input class="message_input" placeholder="Type your message here..." />
</div>
<div class="send_message">
<div class="icon"></div>
<div class="text">Send/div>
</div>
</div>
Parent Function Call:
$('.send_message').click(function (e) {
return [sendMessage(getMessageText()),sendMessage1(getMessageText1())];
});
$('.message_input').keyup(function (e) {
if (e.which === 13) {
return [sendMessage(getMessageText()),sendMessage1(getMessageText1())];
}
});
here getMessageText1 is child function.
Child Function:
getMessageText1 = function () {
var result="";
var id = Parent_FUNC_INPUT;
$.ajax({
url:"func.php",
type: 'POST',
data: ({id:id}),
async: false,
success:function(data) {
result = data;
}
});
I want to populate [[id]] variable in child function from parent function.
First, I'll do my best to clean up the HTML:
<div class="bottom_wrapper clearfix">
<div class="message_input_wrapper">
<input class="message_input" placeholder="Type your message here..." />
</div>
<div class="send_message">
<div class="icon"></div>
</div>
<div class="text">Send</div>
</div>
Using proper indentation will make things far easier to read. And while we're on the subject, you may want to use dashes - instead of underscores _ in your class names, as that's the common convention.
On to your question, it seems like what you want to do is simply pass an argument to getMessageText1 from within (as you refer to it) a "parent" function bound to an event listener.
So you'd define this "child" function with a single parameter:
function getMessageText1(Parent_FUNC_INPUT) {
...
var id = Parent_FUNC_INPUT;
...
}
And then you can just call it with getMessageText1(value) where value is whatever you want to pass in.
One more note: for readability's sake I recommend you do not name your functions the way you have. Having two functions getMessageText and getMessageText1 will just be a source of confusion later on. Instead, think of something more descriptive, ala getMessageTextFromID.
Hopefully I answered the question you meant to ask. Let me know.
When a state is changed, React triggers componentDidUpdate() method, and by then I do:
componentDidUpdate: function () {
React.render(new SubmitButton, $('.uploader-submit').get(0));
}
As you saw, I'm rendering a SubmitButton when a specific state is changed, but my question is: is this the best behavior to get this feature done?
My scenario is: I'm uploading a photo. When the input[type=file] is changed, I create a new state property and then the componentDidUpdate() is triggered, invoking the SubmitButton.
This is my render() method:
render: function () {
return (
<div className="uploader">
<header className="uploader-header">
<div className="uploader-actions pull-left">
<div className="uploader-submit"></div>
<CancelButton router={this.props.router} />
</div>
<UploadButton callback={this.imageSelectedCallback} />
</header>
<Preview imageUri={this.state.imageUri} />
</div>
)
}
Couldn't I do something like the <Preview /> component? I mean, it is there, but something just appears when this.state.imageUri is different of null. This is the implementation of Preview:
var Preview = {
render: function () {
return (
<img src={this.props.imageUri} />
)
}
};
module.exports = React.createClass(Preview);
Yes, I know — "Preview" is invisible by default because it is an image, but I want to know if there's another approach to reach what I want: to show something based on a state, using the render method.
React doesn't render falsy values, be it a component or an attribute (like in the Preview case), e.g.
<div>{null}</div>
<img src={null} />
renders to
<div></div>
<img/>
So typically you just create a variable and conditionally assign it a component or null as was also suggested in another answer:
var button = null;
if(myConditionForShowingButton) {
button = <SubmitButton />;
}
-- or simply --
var button = myConditionForShowingButton ?
<SubmitButton /> :
null;
In cases where the component gets bigger it's typically more readable and cleaner to have a subroutine for rendering that part
var complexComponent = condition ?
this.renderComplexComponent() :
null
Yes. If-Else in JSX.
render: function () {
var submitButton;
if (this.state.imageSelected)
submitButton = <SubmitButton />;
return (
<div className="uploader">
<header className="uploader-header">
<div className="uploader-actions pull-left">
<div className="uploader-submit">{ submitButton }</div>
<CancelButton router={this.props.router} />
</div>
<UploadButton callback={this.imageSelectedCallback} />
</header>
<Preview imageUri={this.state.imageUri} />
</div>
)
}