Simple calculator object

See title.

by KooiInc MeHere

HTML

<input id="v1" type="text" style="width:5em;"/>
<button onclick="calculator.sum();"> + </button>
<button onclick="calculator.multiply();"> * </button>
<button onclick="calculator.div();"> / </button>
<button onclick="calculator.mod();"> % </button>
<input id="v2" type="text" style="width:5em;"/>
<span id="result"> </span>

JavaScript

var Calculator = function(inp1,inp2,reslt) {
    this.valinp1 = inp1;
    this.valinp2 = inp2;
    this.result  = reslt;
    if (!Calculator.prototype.sum) {
      Calculator.prototype.sum = function() {
          var value1 = Number(this.valinp1.value),
              value2 = Number(this.valinp2.value);
          
           this.result.innerHTML = 
            (!/[0-9]/.test(String(value1)) || !/[0-9]/.test(String(value1))) 
             ? 'we only eat digits!' 
             : (value1 + value2);
       };
       Calculator.prototype.multiply = function() {
          var value1 = Number(this.valinp1.value);
          var value2 = Number(this.valinp2.value);
          this.result.innerHTML = 
           (!/[0-9]/.test(String(value1)) || !/[0-9]/.test(String(value1))) 
           ? 'we only eat digits!' 
           : (value1 * value2);
       };
       Calculator.prototype.div = function() {
          var value1 = Number(this.valinp1.value);
          var value2 = Number(this.valinp2.value);
          var restmp = value1/value2;
          this.result.innerHTML = 
           (!/[0-9]/.test(String(value1)) || !/[0-9]/.test(String(value1)) || value2 === 0) 
           ? 'we only eat digits and second value can\'t be zero!' 
           : restmp%1 ? restmp.toFixed(3) : restmp;
       };
       Calculator.prototype.mod = function() {
          var value1 = Number(this.valinp1.value);
          var value2 = Number(this.valinp2.value);
          var restmp = value1%value2;
          this.result.innerHTML = 
           (!/[0-9]/.test(String(value1)) || !/[0-9]/.test(String(value1)) || value2 === 0) 
           ? 'we only eat digits and second value can\'t be zero!' 
           : value1%value2;
       };
    }
},
calculator = 
    new Calculator (
        document.getElementById('v1'),
        document.getElementById('v2'),
        document.getElementById('result')
    );