Example analysis of JS limit condition complementary problem _javascript skill

In this paper, we analyze the problem of JS limit condition completion. Share to everyone for your reference, specific as follows:

Topic I. A and b two variables, without the third variable to switch two variable values

var a=5;
var b=6;
A=a+b;
B=a-b;
A=a-b;
alert (a);
alert (b);

Topic Two. There is a number of n=5, without a For loop, how to return an array of [1,2,3,4,5]

Method I. Traversal with recursive return

var n=5;
Function Show () {
  var arr=[];
  Return (function () {
    arr.unshift (n);
    n--;
    if (n!=0) {
      Arguments.callee ();
    }
    return arr;
  }) ();
}
Alert (Show (n));

Method Two. Matching the number of simulations with regular

var n=5;
var arr=[];
arr.length=n+1;
var arr2=[];
var str=arr.join ("a"); The middle connector with a, to six number only five commas, so length=n+1
var re=/a/g;
Str.replace (Re,function () {
  arr2.unshift (n--);
});
alert (ARR2);

Topic Three. A few n, when N<100 returns N, otherwise returns 100, but cannot use if else, three mesh, switch, etc.

Method one. Math.min

var n=150;
Function Show () {return
  math.min (n,100);
}
Alert (Show (n));

Method two. Sort by array

var n=50;
Function Show () {
  var arr=[n,100];
  Arr.sort ();
  return arr[0];
}
Alert (Show (n));

Method Three. According to the length of the digital rotation string, use the For loop, if the length is less than 3, return itself, greater than or equal to 3 to return 100

var n=150;
Function Show () {
  var str= "n";
  for (;str.length<3;) {return
     n;
  }
  for (;str.length>=3;) {return
  }
}
Alert (Show (n));

Method Four. JSON

var n=50;
Function Show () {
  var json={};
  var m=n<100| | Json M is a Boolean value for
  (Var attr in M) {return
    ;
  }
  return n;
}
Alert (Show (n));

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I hope this article will help you with JavaScript programming.