Calculator setup.

equations/src/App.js

@@ -17,16 +17,47 @@ function Equation(p) {
 	}}>
 	{Object.keys(data).map((key)=><option key={key} value={key}>{key}</option>)}
 	</select><br/>
-	{data[field]}</div><div style={{display:"inline-block",border:"1px solid black"}}>
+	{data[field]}</div>{operator!=="disabled"&&<div style={{display:"inline-block",border:"1px solid black"}}>
 	<select onChange={(ev)=>{updateEquation(field,ev.currentTarget.value)}}>
-	{["+","-","x","÷","()"].map((key)=><option key={key} value={key}>{key}</option>)}
-	</select><br/>{id}</div></>
+	{["+","-","×","÷","()"].map((key)=><option key={key} value={key}>{key}</option>)}
+	</select><br/> </div>}</>
 }
 
 function EquationBuilder(p) {
 	const {data} = p
 	const [equationParts,setEquationParts] = useState([])
 	const [equation,setEquation] = useState([])
+	
+	function SolveEquation(eq) {
+		var newEq = [...eq]
+		//Multiplication and Division first.
+		for (var i=0;i<newEq.length-1;i++) {
+			if (newEq[i]==="×") {
+				var product = Number(newEq[i-1])*Number(newEq[i+1])
+				newEq.splice(i-1,3,product)
+				i--
+			} else
+			if (newEq[i]==="÷") {
+				var quotient = Number(newEq[i-1])/Number(newEq[i+1])
+				newEq.splice(i-1,3,quotient)
+				i--
+			}
+		}
+		for (var i=0;i<newEq.length-1;i++) {
+			if (newEq[i]==="+") {
+				var sum = Number(newEq[i-1])+Number(newEq[i+1])
+				newEq.splice(i-1,3,sum)
+				i--
+			} else
+			if (newEq[i]==="-") {
+				var difference = Number(newEq[i-1])-Number(newEq[i+1])
+				newEq.splice(i-1,3,difference)
+				i--
+			}
+		}
+		return newEq.slice(0,-1)
+	}
+	
 	useEffect(()=>{
 		var newEq = []
 		for (var i=0;i<equationParts.length;i++) {
@@ -39,9 +70,10 @@ function EquationBuilder(p) {
 		<button onClick={()=>{
 			setEquationParts([...equationParts,{field:Object.keys(data)[0],operator:"+"}])}}>+</button>
 		<br/><br/>
-		{equationParts.map((eq,i)=><Equation equationParts={equationParts} setEquationParts={setEquationParts} id={i} data={data} field={equationParts[i].field} operator={equationParts[i].operator}/>)}
+		{equationParts.map((eq,i)=><Equation key={i} equationParts={equationParts} setEquationParts={setEquationParts} id={i} data={data} field={equationParts[i].field} operator={i!==equationParts.length-1?equationParts[i].operator:"disabled"}/>)}
 		<br/><br/>
-		{equation}
+		{equation.slice(0,-1)}
+		<br/><h1>{SolveEquation(equation)}</h1>
 		</>
 }
 

package-lock.json

@@ -0,0 +1,6 @@
+{
+  "name": "EquationsBuilder",
+  "lockfileVersion": 2,
+  "requires": true,
+  "packages": {}
+}