So let me preface this with the fact that I'm doing this coding in Codecademy so maybe its just that being weird.
I am trying to remove all punctuation from an array (dupBW) and set everything to lowercase.
My code works fine within the forEach, the console.log shows that. But then dupBW is unaffected when I log it out at the end.
Thanks for the help.
dupBW.forEach(dupWord => {
if(puncArray.includes(dupWord[dupWord.length-1])) {
dupWord = dupWord.slice(0, dupWord.length-1);
dupWord = dupWord.toLowerCase();
console.log(dupWord);
}
});
console.log(dupBW.join(' '));
Change forEach to map and return dupWord at the end, and it will work; by assigning the array to the newly returned one. Array.prototype.map returns a new array with the return values of the callbacks.
dupBW = dupBW.map(dupWord => {
if(puncArray.includes(dupWord[dupWord.length-1])) {
dupWord = dupWord.slice(0, dupWord.length-1);
dupWord = dupWord.toLowerCase();
console.log(dupWord);
}
return dupWord;
});
console.log(dupBW.join(' '));
If you see in the documentation for .forEach() you will find that forEach does not modify the array it is called on. For that, you can use regular for loop or map or reduce.
You can do the following,
let res = dupBW.map(dupWord => {
if(puncArray.includes(dupWord[dupWord.length-1])) {
dupWord = dupWord.slice(0, dupWord.length-1);
dupWord = dupWord.toLowerCase();
console.log(dupWord);
}
return dupWord;
});
console.log(res.join(' '));
Related
I'm trying to add an item in a specific index inside an array inside a map function and it's been behaving unexpectedly. Here's the code for it
const addItemToLevelTwoArray= (uniqueID, arrayID )=> {
const reportObject = {
id:arrayID,
title:'',
}
data.map(section=>{
section.content.map((report, reportIndex)=>{
if(report.id===uniqueID){
section.content.splice(reportIndex, 0, reportObject);
}
return report;
})
return section;
})
}
Here's a working pen - https://codepen.io/raufabr/pen/vYZYgOV?editors=0011
Expected behaviour is that it would insert an object in the specific index, right above the object where the ID matches.
However, it's acting weirdly and sometimes I'm getting 2 items being added instead of one.
Any tip on what I'm doing would be massively appreciated! I know I'm close but I've been stuck on this for a while now and can't figure out what I'm doing wrong!
Preface: You're using map incorrectly. If you're not using the array that map builds and returns, there's no reason to use it; just use a loop or forEach. More in my post here. And one reason to use an old-fashioned for loop is that you're in control of iteration, which matters because...
However, it's acting weirdly and sometimes I'm getting 2 items being added instead of one.
That's because you're inserting into the array being looped by the map, so on the next pass, it picks up the entry you're adding.
If you do a simple loop, you can easily avoid that by incrementing the index when you insert, or by looping backward; here's the looping backward approach:
const addItemToLevelTwoArray = (uniqueID, arrayID) => {
const reportObject = {
id: arrayID,
title: "",
};
for (const section of data) {
for (let reportIndex = section.content.length - 1; reportIndex >= 0; --reportIndex) {
const report = section.content[reportIndex];
if (report.id === uniqueID) {
section.content.splice(reportIndex, 0, reportObject);
}
}
}
};
Because we're looping backward, we won't pick up the entry we just added on the next pass.
Since the outer loop doesn't have that problem, I used the more convenient for-of.
Since you asked about map, if you do use the array map returns, you can do this by returning an array with the two entries, and then calling flat on the array map builds. (This only works if the array doesn't already contain arrays, because they'll get flattened to.) This is common enough that it's combined in one function: flatMap. It's not what I'd do (I'd do a loop), but it's certainly feasible. Sticking with forEach and flatMap rather than using for-of and for:
const addItemToLevelTwoArray = (uniqueID, arrayID) => {
const reportObject = {
id: arrayID,
title: "",
}
data.forEach(section => {
section.content = section.content.flatMap(report => {
if (report.id === uniqueID) {
// Return the new one and the old one
return [reportObject, report];
}
// Return just the old one
return report;
});
});
};
That assumes it's okay to modify the section object. If it isn't, Alberto Sinigaglia's answer shows creating a new replacement object instead, which is handy in some sitautions.
You can just use flatMap:
const data = [
{
content: [
{
id: 1,
title: "a"
},{
id: 3,
title: "c"
},
]
}
]
const addItemToLevelTwoArray= (uniqueID, arrayID )=> {
const reportObject = {
id:arrayID,
title:'',
}
return data.map(section=> {
return {
...section,
content: section.content.flatMap( report =>
report.id === uniqueID
? [reportObject, report]
: report
)
}
}
)
}
console.log(addItemToLevelTwoArray(3, 2))
The following will extend the inner array .contentwithout modifying the original array data:
const data = [ {id: 0,title:'main',content:[{id:1,title:'Hello'},
{id:2,title:"World"}] } ];
const addItemToLevelTwoArray= (uniqueID, arrayID )=> {
const reportObject = {
id:arrayID,
title:'something new!',
}
return data.map(d=>(
{...d, content:d.content.reduce((acc, rep)=>{
if(rep.id===uniqueID) acc.push(reportObject);
acc.push(rep)
return acc;
},[]) // end of .reduce()
})); // end of .map()
}
const res=addItemToLevelTwoArray(1,123);
console.log(res);
availableButtons.forEach(function(part, index) {
console.log(this[index].title)
// this[index].title = intl.formatMessage(this[index].title);
}, availableButtons)
The code above prints the console as follows:
{id: "abc.btn.xyz", defaultMessage: "someMessage"}
This confirms that each object has an id but when I try to execute the commented code it throws an error saying [#formatjs/intl] An id must be provided to format a message.
I used the same array but only a single object separately as follows intl.formatMessage(availableButtons[0].title); this gave me the required result I am just not able to figure out. I tried various ways of passing values in forEach, what am I missing?
forEach does not actually mutate arrays. it's just a shorthand loop called on the array. It's hard to suggest a solution because your intent is not clear.
availableButtons = availableButtons.map(button => {
//do your mutations here
}
might be a start
I think Array#map works better for in this vade
availableButtons.map(part => {
return {
...part,
title: intl.formatMessage(part.title)
};
});
Access the array (availableButtons) directly and update (mutate) with forEach.
availableButtons.forEach(function (part, index) {
console.log("before: ", availableButtons[index].title);
availableButtons[index].title = intl.formatMessage(this[index].title);
console.log("after: ", availableButtons[index].title);
});
Using Logger.log(response.data.phone), I'm getting this in my log:
[{label=work, primary=true, value=5558675309}, {label=work, value=6108287680, primary=false}, {value=6105516373, label=work, primary=false}]
What I want is to return the two phone numbers as 5558675309, 6108287680.
I've tried Logger.log(response.data.phone.value) and that doesn't work. I've tried ...phone['value'], I've tried ...phone[0].value and this one does return the first phone number 5558675309. But I would like it to return all of the value values whenever I put in the phone key. So how would I modify the logger?
response.data.phone is an array you can try looping through it:
Logger.log(response.data.phone.map(phone => phone.value).join(', '));
const response = {data: {phone : [{label:'work', primary:true, value:5558675309}, {label:'work', value:6108287680, primary:false}, {value:6105516373, label:'work', primary:false}] } }
const Logger = { log : console.log};
Logger.log(response.data.phone.map(phone => phone.value).join(', '));
response.data is an array, response.data.phone does not exist. What you want is response.data[n].phone for an integer n. You can do this with a forEach loop.
response.data.forEach((element) => Logger.log(element.phone.value));
If for whatever reason you need support for older browsers you can use the older function syntax:
response.data.forEach(function(element){
Logger.log(element.phone.value)
});
I am building a simple todo app, and I'm trying to get the assigned users for each task. But let's say that in my database, for some reason, the tasks id starts at 80, instead of starting at 1, and I have 5 tasks in total.
I wrote the following code to get the relationship between user and task, so I would expect that at the end it should return an array containing 5 keys, each key containing an array with the assigned users id to the specific task.
Problem is that I get an array with 85 keys in total, and the first 80 keys are undefined.
I've tried using .map() instead of .forEach() but I get the same result.
let assignedUsers = new Array();
this.taskLists.forEach(taskList => {
taskList.tasks.forEach(task => {
let taskId = task.id;
assignedUsers[taskId] = [];
task.users.forEach(user => {
if(taskId == user.pivot.task_id) {
assignedUsers[taskId].push(user.pivot.user_id);
}
});
});
});
return assignedUsers;
I assume the issue is at this line, but I don't understand why...
assignedUsers[taskId] = [];
I managed to filter and remove the empty keys from the array using the line below:
assignedUsers = assignedUsers.filter(e => e);
Still, I want to understand why this is happening and if there's any way I could avoid it from happening.
Looking forward to your comments!
If your taskId is not a Number or autoconvertable to a Number, you have to use a Object. assignedUsers = {};
This should work as you want it to. It also uses more of JS features for the sake of readability.
return this.taskLists.reduce((acc, taskList) => {
taskList.tasks.forEach(task => {
const taskId = task.id;
acc[taskId] = task.users.filter(user => taskId == user.pivot.task_id);
});
return acc;
}, []);
But you would probably want to use an object as the array would have "holes" between 0 and all unused indexes.
Your keys are task.id, so if there are undefined keys they must be from an undefined task id. Just skip if task id is falsey. If you expect the task id to possibly be 0, you can make a more specific check for typeof taskId === undefined
this.taskLists.forEach(taskList => {
taskList.tasks.forEach(task => {
let taskId = task.id;
// Skip this task if it doesn't have a defined id
if(!taskId) return;
assignedUsers[taskId] = [];
task.users.forEach(user => {
if(taskId == user.pivot.task_id) {
assignedUsers[taskId].push(user.pivot.user_id);
}
});
});
});
I have an array of nested objects and I have a user, which searches for a room
Here is an array of objects.
I would like to filter an array as soon as user types something
I tried a lot of functions, but nothing worked for me, here is the last example, which failed
search(val: any) {
// if input is clear - show everything, what we have
if (val === '') {
this.roomList = this.roomList;
} else {
//choose the object (objects) where rName = val
this.roomList = this.roomList.staticData.rName.filter(function(o) {
return Object.keys(o).some(function(k) {
return o[k].toString().toLowerCase().indexOf(val) != -1;
})
});
}
}
Could you please help or give me a hint?
You need to apply Array.filter() on roomList instead of staticData propety
this.roomList = this.roomList.filter(function (r) {
return r.staticData.rName.toLowerCase().indexOf(val.toLowerCase()) != -1
});
this.roomList = this.roomList.staticData.rName
This is a wrong starting point, just look at it. Then, rName is not an array, so you can't invoke .filter on it.
Here's how to do it :
this.roomListFiltered = this.roomList.filter(o => new RegExp(val,"i").test(o.staticData.rName) )
new RegExp(val,"i") performs a case-insensitive match.
Also, store the result of the filter in a different variable, otherwise you will lose your original list as it gets filtered out.