# In the level mad-maxer! I've got a problem!help!

loop {
var farthest = null;
var maxDistance = 0;
var enemyIndex = 0;
var enemies = this.findEnemies();

what does “var farthest =null” mean?
what’s null !!!
how i can use it !!!

hope you can understand me … not good at english

loop {
var farthest = null;
var maxDistance = 0;
var enemyIndex = 0;
var enemies = this.findEnemies();

``````// 查看全部敌人，找出最远的那个。
while (enemyIndex < enemies.length) {
var target = enemies[enemyIndex];
enemyIndex ++;
// 是不是有敌人比我们能看到的最远的敌人还要远？
var distance = this.distanceTo(target);
if (distance > maxDistance) {
maxDistance = distance;
farthest = target;}
``````

if (farthest) {
// 干掉最远的敌人！
// 如果敌人血量大于0就保持攻击。
while (farthest.health>0) {
this.attack(farthest);
}
}
}
}

though i passed this level, but i still don’t understand.

Hello and welcome to the forums! First of all, please paste your code between 3 backticks (`) according to the FAQ so we can clearly ready it.

First of all:

It means that you define (create) the variable with a value of `null` (“empty”). If you check this variable now (`if (farthest)`), it will return `false` as long as the value is `null`. As soon as you give it another value, the check will return `true` because the variable is not “empty” anymore.

``````loop {    // repeat the below instructions "forever"
/*
* define variables
*/

while {    // go through the list of enemies
if {   // if the current enemy is farther than 'maxDistance'
/*
* (note: 'maxDistance' is originally zero)
* then store its distance in 'maxDistance'
* and make this enemy the 'farthest'
*/
} // end if
} // end while

/*
* Note: at the end of the 'while' loop, when you went through all the enemies
* 'farthest' will contain the name of the enemy that is the farthest from you
*/

if (farthest) {    // if 'farthest' enemy exists (so it's not 'null')
// (note: there will be a 'farthest' enemy as long as there are enemies)
while (farthest.health > 0) { // as long as it's alive
// attack it
} // end while
} // end if

} // end loop
``````

I hope this helps

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