Javascript:言語

Basics

const

        const PROG_VERSION = "version 0.0.a.0"
      

Date

        function PerformanceCounter()
        {
            this.baseCount = 0;
            this.lapCount = 0;
            this.clear = function() {
                this.baseCount = 0;
                this.lapCount = 0;
            };
            this.start = function () {
                this.baseCount = new Date();
                this.lapCount = this.baseCount;
            };
            this.lap = function() {
                var lap = new Date();
                var elapsed = lap - this.lapCount;
                this.lapCount = lap;
                return elased;
            }
            this.stop = function() {
                var lap = new Date();
                return (lap - this.baseCount);
            }
        }
      

継承

        function extend(s, c)
        {
            function f(){};
            f.prototype = s.prototype;
            c.prototype = new f();
            c.prototype.__super__ = s.prototype;
            c.prototype.__super__.constructor = s;
            c.prototype.constructor = c;
            return c;
        };

        ButtonBase = function() {
            console.log("ButtonBase");
            this.sayA = function() { console.log("A"); };
        };

        ButtonA = extend(ButtonBase, function() {
            this.__super__.constructor();
            console.log("ButtonA");
            this.sayB = function() { console.log("B"); };
        });

        var o = new ButtonA();
        o.sayA();
        o.sayB();
      

引数

引数の数を検査する。

        if ( arguments.length >= 1 ) {
          ...
        }
      

引数の数で処理を変える。

        function MyObj() {
          this._prop = {};
          this.set = function() {
              switch(arguments.length) {
              case 1:
                  var spec = arguments[0];
                  for(name in spec) {
                      this._prop[name] = spec[name];
                  }
                  break;
              case 2:
                  this._prop[arguments[0]] = arguments[1];
                  break;
              }
          };
          this.get = function(name) {
              return this._prop[name];
          };
        }

        MyObj myObj = new MyObj();
        myObj.set("a", "1");
        myObj.set({ a: 1, b: 2, c: 3});