Why does my boolean not evaluate correctly?-CodePudding

So, as the title says, my boolean does not evaluate correctly, here is my code:

var unindexed_frmVersionCtrl = $("#frmVersionCtrl").serializeArray();

    unindexed_frmVersionCtrl[unindexed_frmVersionCtrl.length] = { name: "versionControl", value: 0 };
    console.log(unindexed_frmVersionCtrl);


    let historyEntry = false;

    for (const [key, value] of Object.entries(unindexed_frmVersionCtrl)) {

        if (value.name == "versionControlBool") {
            historyEntry = value.value;
            console.log(historyEntry);
        }

        if (value.name == "versionControl") {
            console.log(historyEntry);
            if (historyEntry == true) {
                value.value = 1;
                console.log("lel");
            }
            else {
                console.log("false");
                value.value = 0;
            }
        }
    }

    console.log(unindexed_frmVersionCtrl);

here is the output:

historyEntry evaluates to true even when it is false. I don't know what to do. No idea. I am just starting out with javascript and I have never been this confused. Thanks.

EDIT: typo.

CodePudding user response：

The problem is your historyEntry = value.value;, in this case value.value is a string, not a bool.

You can do historyEntry = (value.value == 'true');

Demo

var unindexed_frmVersionCtrl = [{
  "name": 'versionControlBool',
  value: 'true'
}, {
  "name": 'versionCount',
  value: '25'
}, {
  "name": 'versionControl',
  value: 0
}]

var historyEntry = false;

for (const [key, value] of Object.entries(unindexed_frmVersionCtrl)) {
  if (value.name == "versionControlBool") {
    historyEntry = (value.value == 'true');
    console.log("typeof value.value = "   typeof(value.value))
    console.log(historyEntry);
  }

  if (value.name == "versionControl") {
    console.log(historyEntry);
    if (historyEntry == true) {
      value.value = 1;
      console.log("lel");
    } else {
      console.log("false");
      value.value = 0;
    }
  }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

CodePudding user response：

The value of 'versionControlBool' is a string 'true' not boolean true. If you try 'true' == true you'll get false but if you console.log('true') the console will log true as if it's a boolean so you wouldn't notice. Here's some code to try it out.

var x = true;
var y = 'true';

console.log(x, 'This is the boolean true');
console.log(y, 'This is a string "true"');

console.log(x == true, 'This should be true');
console.log(y == true, 'This will be false even though the console thinks it\'s a boolean');

console.log(y == 'true', 'Whereas this will be true, as it should');