Detailed explanation of the sample code for javascript to traverse the key of a json object and any js object attribute (picture)

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Use the keys method to obtain the properties and methods of the object:

 function Pasta(grain, width, shape) {
        this.grain = grain;
        this.width = width;
        this.shape = shape;
        this.toString = function () {
          return (this.grain + ", " + this.width + ", " + this.shape);
        }
      }
      
      var spaghetti = new Pasta("wheat", 0.2, "circle");
      var arr = Object.keys(spaghetti);
      document.write(arr);

Result picture:

Displays the names of all enumerable properties starting with the letter "g" in the Pasta object:

function Pasta(grain, width, shape) {
        this.grain = grain;
        this.width = width;
        this.shape = shape;
      }

      function CheckKey(value) {
        var firstChar = value.substr(0, 1);
        if (firstChar.toLowerCase() == "g") {
          return true;
        } else {
          return false;
        }
      }

      var polenta = new Pasta("corn", 1, "mush");
      var keys = Object.keys(polenta).filter(CheckKey);
      document.write(keys);

The result is as shown:

Traverse the keys of the json object:

var an_obj = { 100: 'a', 2: 'b', 7: 'c', "name": "wu", "interesting": "Game" };
 document.write(Object.keys(an_obj));

The result is as shown:

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