是否可以在 javascript 的一个循环中将结果数减少 7、3、2？

Question

I'm new to javascript and my weakness has always been for-loops. However, right now I'm 95% sure, that I need to use for-loops to achieve my goal.

For an instance: I'm trying to decrement number 45 at first by 7, till it reaches 38:

for (var j = 45; j >= 38; j -=7){
console.log (j);
}

Then I would like to decrement 38 by 3, till it reaches 32:

for (var l = 38; l >= 32; l -=3){
console.log (l);
}

And then again decrement result by 2 till it reaches 0:

for (var s = 32; s >= 0; s -=2){
console.log (s);
}

And here's the issue that I'm facing: how can I assign these 3 for-loops to one variable, so that when I'm calling for variable, it displays:

45
38
35
32
30
28
.
.
0

Or is there a better alternative?

Thanks!

Answer 1

Is it possible to decrement result number by 7, 3, 2 in one loop in javascript?

Yes, it is possible.

You could take an object with the values for changing the step variable for the wanted interval.

 var steps = { 45: 7, 38: 3, 32: 2 }, step, j; for (j = 45; j >= 0; j -= (step = steps[j] || step)) { console.log(j); }

 .as-console-wrapper { max-height: 100%;important: top; 0; }

Answer 2

You can do it a single for loop like the following way:

 for (var j = 45; j >= 0; ){ console.log (j); if (j>38) j -= 7; else if (j>32) j -= 3; else j -= 2; }

Answer 3

You can just modify your iteration interval depending on what range your current iterator is in.

var x = 7;
for( var i = 45; i > 0; i -= x )
{
    if( i <= 38 && i > 32 ) x = 3;
    else if( i <= 32 ) x = 2;
    console.log( i );
}