How to render v-for from particular index - vue.js

I want to loop in v-for from suppose from number 5 to 10 .
The loop want to be started at 5 and end at 10.
I have tried this
<div v-for="n in 10" v-if="n>=5"></div>
But I want more effective way of doing the loop . Does anyone knows how to do so that loop starts at 5 ?

Its possible for your example:
<div v-for="i in range(5, 10)">
... some code here
</div>
and mount range function:
var app = new Vue({
el: '#app',
methods:{
range : function (start, end) {
return Array(end - start + 1).fill().map((_, idx) => start + idx)
}
}
});
and sample in jsfidle.
If want know more than this github issue can help you.

Also try this simple approach:
new Vue({
el: '#test',
data: {
items: [
'1',
'2',
'3',
'4',
'5',
'6',
'7',
'8',
'9',
'10'
]
},
methods: {
sliceItems: function (start, end) {
return this.items.slice(start, end);
}
}
})
<script src="https://unpkg.com/vue#2.4.2/dist/vue.min.js"></script>
<div id="test">
<ul>
<li v-for="(item, index) in sliceItems(5,10)" >{{ item }}</li>
</ul>
</div>

Another simple alternative is to just use basic +/-:
new Vue({
el: '#app',
data: {
start: 5,
end: 10
}
})
<script src="https://unpkg.com/vue"></script>
<div id="app">
<ul>
<li v-for="i in end-start" >{{ i+start }}</li>
</ul>
</div>
If you really need to use {{ i }} a lot of times and is bothered by adding start, you can use a little trick:
new Vue({
el: '#app',
data: {
start: 5,
end: 10
}
})
<script src="https://unpkg.com/vue"></script>
<div id="app">
<ul>
<template v-for="curr in end-start" >
<li v-for="i in [curr+start]">
{{ i }}{{ i }}{{ i }}{{ i }}{{ i }}{{ i }}{{ i }}{{ i }}{{ i }}
</li>
</template>
</ul>
</div>

Related

How can I get the second value in a v-for loop?

So I've got an Object namely:
test:{price: 9, qty:1}
How can I loop through this object and only get the second value namely the qty?
JS:
new Vue({
el: '#app',
data: {
test:{price: 9, qty:1}
}
HTML:
<div v-for="(value, key, index) in test>
{{ value[1] }}
</div>
Since test is an object and you want to access just a single property, so there is no need to loop here you can simply access the object property using . dot notation like:
<div>
{{ test.qty }}
</div>
Demo:
new Vue({
el: '#app',
data: {
test: {
price: 9,
qty: 1
}
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.min.js"></script>
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" rel="stylesheet">
<div id="app">
<div class="card p-2">
Qty: {{ test.qty }}
</div>
</div>

Vue computed function to match elements from 2 different arrays

Currently, I'm working with Vue v2.x.x. I have an array:
sectionTitles = ['Technology', 'Data', 'Poverty and Research', ...]
and I have jobsData that looks like this:
[{'title': 'Software Engineer', mainTag: 'Data', ...}...]
I want to display <li> in an <ul> when the sectionTitle matches the job.mainTag.
I was reading in the Vue docs that you shouldn't combine v-if with v-for, so I created a computed method to be able to filter the jobs. Here is what I did so far:
window.onload = function () {
var app = new Vue({
delimiters: ['${', '}'],
el: '#app',
data: {
jobs: jobsData,
sectionTitles: ['Data','Poverty Research Unit', 'Technology']
},
computed: {
matchingTitles: function (sectionTitle) {
return this.jobs.filter(function (job, sectionTitle) {
job.mainTag === sectionTitle;
})
}
}
})
}
<div id="app">
<template v-for="title in sectionTitles">
<h4 class="h3">{{ title }}</h4>
<ul class="list-none p-0 color-mid-background" id="jobs-list">
<li class="py-1 px-2" v-for="job in matchingTitles(title)">
<a :href="`${job.url}`">
${job.title}
</a>
</li>
</ul>
</template>
</div>
So basically I want to only display <li> when the sectionTitle (for example Data) matches the job.mainTag. How can I go about achieving this in Vue?
Change your computed method to just a method. Then change your filter to return a value. Also for displaying in Vue you want to use {{....}} not ${...}
new Vue({
el: '#app',
data: {
jobs: [{'title': 'Software Engineer', mainTag: 'Data'}],
sectionTitles: ['Data','Poverty Research Unit', 'Technology']
},
methods: {
matchingTitles: function (sectionTitle) {
return this.jobs.filter ((job)=>{
return job.mainTag === sectionTitle;
})
}
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<template v-for="title in sectionTitles">
<h4 class="h3">{{ title }}</h4>
<ul class="list-none p-0 color-mid-background" id="jobs-list">
<li class="py-1 px-2" v-for="job in matchingTitles(title)">
<a :href="job.url">
{{job.title}}
</a>
</li>
</ul>
</template>
</div>
#depperm's answer works well (+1), but I'll offer a more render-efficient alternative. Computed properties are cached, so you could avoid the work of matchingTitles() on re-render. In addition, it might be easier to comprehend the template alone without having to jump to the implementation of matchingTitles().
I recommend computing the entire list to be iterated, mapping sectionTitles to the appropriate iterator object:
computed: {
items() {
return this.sectionTitles.map(title => ({
title,
jobs: this.jobs.filter(job => job.mainTag === title)
}))
}
}
Then, you'd update the references in your template to use this new computed prop:
<template v-for="item in 👉items👈">
<h4>{{ item.title }}</h4>
<ul>
<li v-for="job in 👉item.jobs👈">
<a :href="job.url">
{{ job.title }}
</a>
</li>
</ul>
</template>
new Vue({
el: '#app',
data: {
jobs: [{'title': 'Software Engineer', mainTag: 'Data'}],
sectionTitles: ['Data','Poverty Research Unit', 'Technology']
},
computed: {
items() {
return this.sectionTitles.map(title => ({
title,
jobs: this.jobs.filter(job => job.mainTag === title)
}))
}
}
})
<script src="https://unpkg.com/vue#2.6.11/dist/vue.min.js"></script>
<div id="app">
<template v-for="item in items">
<h4 class="h3">{{ item.title }}</h4>
<ul class="list-none p-0 color-mid-background" id="jobs-list">
<li class="py-1 px-2" v-for="job in item.jobs">
<a :href="job.url">
{{ job.title }}
</a>
</li>
</ul>
</template>
</div>

How to bind data in a link inserted to a v-html in vuejs?

Here's my code:
<pre
class="pre-text-formatted feed mt-2"
v-html="post.description.length >= 200 ? post.description.substring(0,200) + `... <a #click='readMore' class='text-muted pull-right' href>...read more</a>` : post.description">
</pre>
And here's the output:
The readMore method does not trigger its function.
Hello I personally don't like using v-html except in some rare cases. For this question I will suggest you render your templates conditionally. here's a sample that might help.
var app = new Vue({
el: '#app',
data: {
post: {
description: 'Hello you\'re awesome today.',
},
},
methods: {
readMore() {
alert('You click read more');
},
},
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<pre
class="pre-text-formatted feed mt-2">
<template v-if="post.description.length >= 200">
{{ post.description.substring(0,200)}} <a #click='readMore' class='text-muted pull-right' href>...read more</a>
</template><template v-else>{{post.description}}</template>
</pre>
</div>
you should try with conditional rendering, as below:
<pre
class="pre-text-formatted feed mt-2">
<template v-if="post.description.length >= 200">
{{ post.description.substring(0,200) }}...
<a #click='readMore' class='text-muted pull-right' href>...read more</a>
</template>
<template v-else>
{{ post.description }}
</template>
</pre>

Conditional a href in Vuejs

I am rendering a list of store titles in VueJS, some of them have a url property, some of them don't. If the title has a url, I want to add a a href property:
<div v-for="(store, index) in stores">
<span v-if="store.link"><a :href="store.link" target="_blank">{{ store.title }}</a></span>
<span v-else="store.link">{{ store.title }}</span>
</div>
This works, but the code looks duplicated. Is there anyway to simplify the code further?
you can use component tag:
var app = new Vue({
el: '#app',
data () {
return {
stores: [
{title:'product1',link:'/products/222'},
{title:'product2'},
{title:'product3',link:'/products/333'},
{title:'product4'}
]
}
}
})
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<div id="app">
<div v-for="(store, index) in stores">
<component :is="store.link?'a':'span'" :href="store.link || ''" target="_blank">{{store.title}}
</component>
</div>
</div>
I'd remove the first span element, as it's not necessary. Also, the v-else does not need the conditional statement (it's not v-else-if):
new Vue({
el: '#app',
data: {
stores: [
{ link: 'foo', title: 'foo-text' },
{ title: 'bar-text' }
]
}
})
<script src="https://unpkg.com/vue"></script>
<div id="app">
<div v-for="(store, index) in stores" :key="index">
<a v-if="store.link" :href="store.link" target="_blank">{{ store.title }}</a>
<span v-else>{{ store.title }}</span>
</div>
</div>
You can use dynamic arguments in vue3
https://v3.vuejs.org/guide/template-syntax.html#dynamic-arguments
<a v-bind:[attributeName]="url"> ... </a>
or binding an object of attributes
<div v-bind="{ id: someProp, 'other-attr': otherProp }"></div>

Any easier way to access nested object properties in Vue template?

It's convenient to group data into nested object properties. By doing this, we don't have to collect properties from the data field into an entity for later use. As in the following example,
var demo = new Vue({
el: '#demo',
data: {
level1: {
level2: {
level3_1: 'Hello',
level3_2: 'world'
}
}
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.4.2/vue.min.js"></script>
<div id="demo">
<div class="person">
<h3>{{ level1.level2.level3_1 }}</h3>
<p>{{ level1.level2.level3_2 }}</p>
</div>
</div>
However, it's really overkill having to type the "level1.level2" prefix in order to get to the level3_x field. It'll be very cumbersome if there're loads of level3 fields.
I wonder if there is any way that I can save the work for typing level1.level2 over and over again. Does the template have any syntax so that some section is under the scope of "level1.level2"? Does Vue provide any support so that in this case the prefix "level1.level2" is assumed?
There are a couple of options.
1. Use v-for
Everything inside the v-for block is scoped to the level that you're iterating over. Do it like this:
var demo = new Vue({
el: '#demo',
data: {
level1: {
level2: {
level3_1: 'Hello',
level3_2: 'world'
}
}
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.4.2/vue.min.js"></script>
<div id="demo">
<div class="person">
<template v-for="(l2prop, l2propName) in level1">
<h3>{{ l2prop.level3_1 }}</h3>
<p>{{ l2prop.level3_2 }}</p>
</template>
</div>
</div>
2. Use a component
Components get a subset of their parent's data, so they're automatically scoped. Do it like this:
Vue.component( "person", {
props: ['data'],
template: '<div class="person"><h3>{{ data.level3_1 }}</h3><p>{{ data.level3_2 }}</p></div>'
});
var demo = new Vue({
el: '#demo',
data: {
level1: {
level2: {
level3_1: 'Hello',
level3_2: 'world'
}
}
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.4.2/vue.min.js"></script>
<div id="demo">
<person v-bind:data="level1.level2"></person>
</div>
The example of #jason-smith is almost right. v-for is used for arrays or lists. To make it work is necessary to put your object in list.
Following his example the better approach would be
var demo = new Vue({
el: '#demo',
data: {
level1: {
level2: {
level3_1: 'Level 3_1',
level3_2: 'Level 3_2'
}
}
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="demo">
<div class="person">
<template v-for="level2Obj in [level1.level2]">
<h3>{{ level2Obj.level3_1 }}</h3>
<p>{{ level2Obj.level3_2 }}</p>
</template>
</div>
</div>
There are serval ways:
Use a method that gets the same level
methods:{
getLvl3: function(nr){
return this["level"+nr]["level"+nr]["level3_"+nr];
}
{{ getLvl3(1) }}
Iterate over with v-for v-for docu
example:
<div id="demo">
<div class="person">
<template v-for="(lvl2, key) in level1">
<template v-for="(lvl3, key) in lvl2">
<h3 v-if="key === 'level3_1'>{{ lvl3 }}</h3>
<p v-if="key === 'level3_2'">{{ lvl3 }}</p>
</template>
</template>
</div>
</div>
bind to variable that is defined outside of vue:
var nested = { level1: { level2: { level3_1: 'Hello', level3_2: 'world' }}
and inside of vue component or instance:
data:{
level2: nested.level1.level2,
}
<div id="demo">
<div class="person">
<h3>{{ level2.level3_1 }}</h3>
<p>{{ level2.level3_2 }}</p>
</div>
</div>