The odd for loop notation in JS (JavaScript)!

This article introduces JS development for the JavaScript Intensive tutorial series

Recently, in an interview, I've seen a couple of these for loops. The first reaction is to be ignorant.

After a closer look, there's no problem.

First, the code is a normal loop.

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1. for var i=0;i<10;i++{}

This f-cycle is a normal cycle, no problem at all.

The second Kind

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1. for var  i=10;i--;{}   

Cycle result is 10 cycles normal

Third Kind

for (;;);

This would be a dead loop.

Fourth type

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1. for (; 1;) {}

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1. This is still a dead loop.

Let's think about the structure of the For loop for (expression 1 expression 2 expression 3) {loop-body}

Expression 1 is an initial value

Expression 2 is the condition is true when the loop resumes the next time the loop is stopped

Expression 3 is a variable increment

Also note that the dot JS expression can not be written but "" cannot be omitted.

And then we'll analyze a few special ways.

Notation 2 expression 3 omitted but expression 2 is a bear 10 to 0 descending number so in 10~1 when the expression 2 for the true loop at the time of 0 is a false stop loop.

3 All the conditions are not. That must be a dead loop.

notation 4 Expression 2 constant for the true loop has been going on ~ ~ ~ ~ ~ ~ ~ ~ ~ ~!

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The odd for loop notation in JS (JavaScript)!