Question

我正在制作一个计算器，我已经用html和css创建了计算器，但是我试图通过在显示屏上点击注册按钮来向前推进，这就是我现在的问题。我是一个相当陌生的JavaScript，所以如果有人能指出我正确的方向，如何做到这一点或在哪里找到答案我会很感激。

这是我正在处理的部分，试图让按钮'7'注册，以便我可以做其他人。

<div class="container-fluid calc" >
 <div class="display">
  <label type="text" id="screen">0</label>

   <div class="buttons">

     <button onClick='calculate()' id='myButton'>7</button>
     <button>8</button>
     <button>9</button>

这是我放在一起的JS

function calculate(){
  var num = document.getElementById('#myButton').contentValue;
  document.getElementById('screen').innerHTML = num;
}

calculate();

Answer 1

您应该使用.contentValue函数而不是#函数执行此操作，此外，您不应该使用document.getElementById中的function calculate(){ var num = document.getElementById('myButton').innerHTML; document.getElementById('screen').innerHTML = num; } calculate();在jQuery中，所以只需要ID就足够了

{{1}}

希望这有帮助！

Answer 2

您需要从

更新

 var num = document.getElementById('#myButton').contentValue;

到

 var num = document.getElementById('myButton').innerHTML;

Answer 3

更新

function calculate(){
  var num = document.getElementById('#myButton').contentValue;
  document.getElementById('screen').innerHTML = num;
}

到

function calculate(){
  var num = document.getElementById('myButton').innerText;
  document.getElementById('screen').innerText = num;
}

Answer 4

另一种选择是你可以这样的数据属性：

#include <iostream>
#include <string>
#include <functional>

class AbstractSolver {
  public:
  virtual ~AbstractSolver(){}
  virtual double solve() = 0;
  virtual void setSystem(std::function<double(double,double)> system) = 0;
};

class ConcreteSolver : public AbstractSolver {
  protected:
    double stepSize;
    double initialValue;
    std::function<double(double, double)> system;
  public:
  ConcreteSolver(double stepSize,
                 double initialValue) :
     stepSize(stepSize),
     initialValue(initialValue) {}

  double solve() {
    // implementation here ...
  }

  void setSystem(std::function<double(double,double)> system) {
    this->system = system;
  }
};

class Model {
  protected:
    std::function<double(double,double,double)> system;
    AbstractSolver * solver;
  public:
    Model(AbstractSolver * solver,
          std::function<double(double, double, double)> system ) {
      this->solver = solver;
      this->system = system;
    }

    ~Model() {
       delete solver;
    }

    double getSolution(double tau) {
      std::function<double(double, double)> sys =
          [this, tau](double t, double y) { return system(t, y, tau); };
      solver->setSystem(sys); // SIGSEGV
      return solver->solve();
    }
};

int main(){
  std::function<double(double, double, double)> system = 
    [](double t, double y, double tau) {
         return 0;// return some mathematical expression
      };
  AbstractSolver * solver = new ConcreteSolver(0, 1);
  Model model = Model(solver, system);
  model.getSolution(0.1);

}

并且这样：

<button onClick='calculate()' id='myButton' data-value="7">7</button>

使用JavaScript从HTML按钮获取值

4 个答案: