JavaScript: Calculator using variables

Question

I have a problem where I can't get my JavaScript calculator to work. When displayed in a browser, that part shows the actual code lines instead of the returned answer. This is what I have so far. The calculation is in the function b(), and printed in the document.write() on the bottom.

JavaScript:

//*Note that this is an external JavaScript file*
function a(a1,a2,a3) {
    this.a1 = a1;
    this.a2 = a2;
    this.a3 = a3;
    this.a4 = b;
}

var abc = new a("2", "80", "1000");
var def = new a("1.5", "40", "512");
var ghi = new a("1", "20", "256");

//Below is the calulation function I'm having problems with
function b() {
    var calculation;
    calculation = 500;
    calculation+=(this.a1 = 2) ? 200 : 100;
    calculation+=(this.a2 = 80) ? 50 : 25;
    calculation+=(this.a3 = 1000) ? 150 : 75;
    return calculation;
}

var returned_value_abc = abc.a4();
var returned_value_def = def.a4();
var returned_value_ghi = ghi.a4();

document.write("Abc object: ");
document.write("<br/>");
//Below is code to print out returned calculation value
document.write("Value: "+abc.a4);
document.write("<br/>");
document.write("<br/>");
document.write("Def object: ");
document.write("<br/>");
//Below is code to print out returned calculation value
document.write("Value: "+def.a4);
document.write("<br/>");
document.write("<br/>");
document.write("Ghi object: ");
document.write("<br/>");
//Below is code to print out returned calculation value
document.write("Value: "+ghi.a4);

Do not use document.write: http://stackoverflow.com/questions/802854/why-is-document-write-considered-a-bad-practice — Anthony Garcia-Labiad, Sep 06 '14 at 11:27

score 5 · Answer 1 · answered Sep 06 '14 at 11:31

Your problem is most likely these lines:

calculation+=(this.a1 = 2) ? 200 : 100;
calculation+=(this.a2 = 80) ? 50 : 25;
calculation+=(this.a3 = 1000) ? 150 : 75;

The = in the parenthesis is an assignment, not an equality comparison. Use

calculation += (this.a1 == 2) ? 200 : 100;
calculation += (this.a2 == 80) ? 50 : 25;
calculation += (this.a3 == 1000) ? 150 : 75;

JavaScript: Calculator using variables

1 Answers1