Javascript "For loops" difference between i-5 and i=-5 [closed] - javascript

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I want a loop that starts with i=100, and decrements by 5 on each iteration. However, this produces an error:
for(var i=100;i>=1;i-5)
{
document.write(i+"<br />");
}
But 'i=i-5' works:
for(var i=100;i>=1;i=i-5)
{
document.write(i+"<br />");
}
Why?
The question is how we can assign a variable to a variable i=i-5.I go the question answered I taught "i=i-5" was a expression the value of i variable is i-5 and no calculation happen its just a stable variable.
The answer is that it is taking a the i value and subtracting it by 5 and not assigning.

If you just write i - 5, there is no left-hand variable, which means there is nothing which is taking the value of i and subtracting it by 5. If you write i = i - 5 then you will decrement 5 since you now have a left-hand variable.

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Number prediction from 1 to 10 from javascript [closed]

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Closed 1 year ago.
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This is my code but when i run this code in console always giving me Congratulations.
Help me for solve this problem.
var val=Math.floor(Math.random() * 10) + 1;
console.log(val);
var Predict = Number(prompt("Prediction ?"));
for(var i=1 ; i <= 3; i++){
if(Predict<val){console.log("Up")};
if(Predict=val){console.log("Congratulations") };
if(Predict>val){console.log("Down")}
}
Equal operator assigns the right hand to the left hand and so the result is always true! To compare two values use double equals like this:
if (Predict==val){console.log("Congratulations") };

Javascript checking if a string lentgh is 0 not working [closed]

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This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 1 year ago.
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I have a JS function which checks if a user entered string is zero.
if (str.legth = 0) {
alert('Provide at least 1 character to create a folder.');
return;
}
But this seems to let a user pass a zero entered string.
Is there anything missing?
THanks
You've misspelled "length" and you need "==" instead of "=" to check for equailty rather than assigning a value.
If your variable is called str, then length is used to return a boolean value. You need to use either == or === for an actual comparison instead of an assignment. Additionally, a return isn't necessary.

Why are consts different to simple objects javascript [closed]

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This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 3 years ago.
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when i work in javascript canvas, when i created a basic object for aqngles like thius
const Angle =
{
Beginning:0*Math.PI,
OneQuarter:0.5*Math.PI,
TwoQuarter:1.0*Math.PI,
End:2*Math.Pi
}
and when i console log the outputs i get this:
0
NaN
but at the same time when i create unique consts for each like so:
const
startAngle = 0*Math.PI,
endAngle = 2*Math.PI;
and i console log it i get the response i want:
0
6.283185307179586
why does this happen? and how can i create a simple object with calculation and get a correct response? Thanks
Repl page:
https://repl.it/#Ballatoilet/EMDR
You have typo, it should be End:2*Math.PI and you have End:2*Math.Pi (small "i" letter).

Regex Issue JavaScript [closed]

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This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 4 years ago.
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I'm trying to take a string and check whether or not it contains a lowercase letter or number, and then if so push that letter or number to an array.
for(let i = 0; i < datearg.length; i++)
{
log.info(datearg.charAt(i));
if(/[a-z]/.test(datearg.charAt(i))) letter_num++; letters.push(datearg.charAt(i));
if(/[0-9]/.test(datearg.charAt(i))) number_num++; numbers.push(datearg.charAt(i));
}
However, both if statements always evaluate to true and the arrays end up containing every single character in datearg. Anyone know why?
if(/[a-z]/.test(datearg.charAt(i))) letter_num++; letters.push(datearg.charAt(i));
is equivalent to
if(/[a-z]/.test(datearg.charAt(i))) { letter_num++; }
letters.push(datearg.charAt(i));
i.e. push is not conditional. This is the primary reason why many style guides heavily discourage control structures without braces (which only take a single statement).

javascript for loop does not work [closed]

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This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 6 years ago.
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I'm creating a site and i needed to do some js. I'm not that good with it but tought i would figer it out. Not. I created a for loop but it does not run.
function order(user,product){
var index;
for(var i = 0; i<users.lenght; i++){
if(user == users[i]){
index = i;
break;
}
}
var budget = budgets[index];
alert(budget);
}
the creation of the users and budgets arrays are done with php and after checking with alert() it was how it should be.
Can anyone help me please?
lenght is spelt length. The misspelt property does not exist, so it undefined, which is equivalent to 0.

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