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I have explore a few webs and watch some videos but I couldn't understand how array.forEach() works
This is the script that I found regarding that
let meals = ["rice", "meat", "salad"];
meals.forEach(capitalize);
meals.forEach(print);
function capitalize(element, index, array){
array[index] = element[0].toUpperCase() + element.substring(1);
}
function print(element){
console.log(element);
}
Can someone explain to me about how array[index] = element(0).toUpperCase() + element.substring(1); and meal.forEach(); works?
forEach() is an array function from JavaScript, that is used to iterate over items in a given array.
element[0] will return first character of each array element.
toUpperCase() is function use to convertthe string into upper case.
element.substring(1) this will return a string, except for the first character.
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I have troubles understanding the meaning of (_,idx) in the following statement
arr.filter((_, idx) => idx % 2 === 0)
I understand it is filtering the array and just returning on the new array all elements that respect the condition(basically with even index). But i do not understand what this (_,idx) means?
Any help?
(_, idx) are two variable names.
arr.filter((currentValue, index, array) => )
As you can read here.
So "_" is currentValue and "idx" is the index.
"_" is not use but still defindes because it is a non-optional parameter, so you always have to give it an name.
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I am working with an array in Javascript that contains several IDs in them but I would like to filter out all non-numeric entries using regex and return that array of just numbers. For example, I have myArray = ['131125150138677','CI%20UW%20SYSTEMS%20S','040964100010832'] where I want to get rid of the second item in the list since it's non-numeric.
So use Filter and test to see if they are numbers
var myArray = ['131125150138677', 'CI%20UW%20SYSTEMS%20S', '040964100010832']
var filtered = myArray.filter(Number)
console.log(filtered)
var filtered2 = myArray.filter(s => s.match(/^\d+$/))
console.log(filtered2)
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Convert
var a = [['12ae11ee12-1bhb222','2019-10-10T19:46.19.632z','a123']]
to
var a= ['12ae11ee12-1bhb222','2019-10-10T19:46.19.632z','a123']
I dont want two square brackets in front and end.
I want output
a[2] = 'a123'
The best way to do is just assigning the first value to the array:
var a = [['12ae11ee12-1bhb222','2019-10-10T19:46.19.632z','a123']];
a = a[0];
console.log(a);
But the right way of dealing it should be making sure that the endpoint or whatever that outputs should output correctly.
You can use Array.prototype.flat().
console.log([['12ae11ee12-1bhb222','2019-10-10T19:46.19.632z','a123']].flat());
This solution works if it's extremely nested too:
console.log([
['12ae11ee12-1bhb222'],
['2019-10-10T19:46.19.632z', 'a123']
].flat());
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Inside a string: I need to replace the number between [ ] by another number with Javascript or jQuery.
What is the best way to proceed ?
Eamples
"[12345].Checked" > "[1].Checked"
"[123].RequestID" > "[21].RequestID"
Thanks for your help.
function fixNum(str, newnum) {
return str.replace(/\[\d+\]/,'[' + newnum + ']')
}
Use .replace:
"[12345].Checked".replace(/\[(\d+)\]/, "[1]") // "[1].Checked"
With regular expressions:
/\[(\d+)\]/
It searches a number (no matter length) inside a [] set.
Combined with replace you can make it.
Test it:
https://regex101.com/r/zT5kD0/1
Use replace method to replace the part
function replaceStr(string,orgText,replaceText){
var res = string.replace(orgText, replaceText);
return res;
}
console.log(replaceStr("[12345].Checked",'12345','1'));
jsfiddle
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I have an array like this:
var animals=["cat","dog","snake","rhino"];
But sometimes I have to delete this array(remove it from the dom).
I have tried animals.remove; and $(animals).remove() and animals.remove() but none of them did the trick.Any ideas?
var animals=["cat","dog","snake","rhino"];
then to clear it do:
animals=[];
or
animals.length=0;
or
while(animals.length > 0) {
animals.pop();
}
Just assign the animals array to a value undefined and the array data will be dereferenced and garbage collected.
Donot try to call delete operator that is explicit removal.
animals = undefined
OR
animals = void 0
Thanks
Just Clear The Array
Using This 2 Methods
animals.length =0
animals=[];