FOR LOOP with nested IF statement

Question

I have some code which loops through an array and adds the data to a HTML table.

For one of the fields 'Unit_Sell', I would like to prefix the HTML with a '£' symbol.

Here is what I have tried.

 for (var i = 0; i < arr.length; i++) {
   var node = win.document.createElement("tr")

   for (var key of ['description', 'ref_date_start', 'ref_date_end', 'unit_sell', 'qty', 'price']) {
     var tb = win.document.createElement("td")

     if (key = 'unit_sell') {
       tb.innerHTML = '£' + arr[i][key]
     }

     tb.innerHTML = arr[i][key]
     tb.style.paddingLeft = "30px";
     node.appendChild(tb)
   }
 }

The loop works fine, but the if statement condition is not being met.

`if (key = 'unit_sell')` [single `=` is for *assignment*](https://stackoverflow.com/questions/11871616/in-javascript-vs/). To do an equality check use `==` or `===` — VLAZ, Nov 18 '19 at 15:32
Change to `key == 'unit_sell'`. You need a double `=` for `if` comparison. — nurdyguy, Nov 18 '19 at 15:32
Even after fixing the typo, you have `tb.innerHTML = ` after the if block which is going to overwrite everything. So it will overwrite the code you set in the if block — Patrick Evans, Nov 18 '19 at 15:34
Thanks Patrick, I needed to add the second "tb.innerHTML =" into an ELSE on the FOR LOOP. Please add as an answer and I will accept — user3580480, Nov 18 '19 at 15:37

score 2 · Accepted Answer · answered Nov 18 '19 at 15:35

As pointed out already you need to compare key to 'unit_sell' instead of assigning. However you also need an else branch, otherwise the innerHTMl from within the condition will be overwritten.

for (var i = 0; i < arr.length; i++) {
  var node = win.document.createElement("tr")

  for (var key of ['description', 'ref_date_start', 'ref_date_end', 'unit_sell', 'qty', 'price']) {
    var tb = win.document.createElement("td")

    if (key === 'unit_sell') {
      tb.innerHTML = '£' + arr[i][key]
    } else {
      tb.innerHTML = arr[i][key]
    }

    tb.style.paddingLeft = "30px";
    node.appendChild(tb)
  }
}

score 0 · Answer 2 · answered Nov 18 '19 at 15:31

0

This is an issue with comparison. You put:

if (key = 'unit_sell') {

When it should be:

if (key == 'unit_sell') {

The way you wrote it, you are using assignment instead of comparison.

answered Nov 18 '19 at 15:31

Jeremy Harris

24,318
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Whoever downvoted, care to explain why this answer is insufficient? – Jeremy Harris Nov 18 '19 at 15:33
I didn't down vote, but I'm guessing it was downvoted due to the `tb.innerHTML = arr[i][key]` line not being in an `else` block after your `if` statement. – Adrian Roworth Nov 18 '19 at 15:41
Ah ok, that's fair. I didn't notice that. – Jeremy Harris Nov 18 '19 at 15:42

score 0 · Answer 3 · answered Nov 18 '19 at 15:32

0

   if (key == 'unit_sell') {
        tb.innerHTML = '£' + arr[i][key]
    }

And a great tutorial for JS https://github.com/getify/You-Dont-Know-JS

answered Nov 18 '19 at 15:32

Safi Nettah

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FOR LOOP with nested IF statement

3 Answers3