有没有办法检查数组中的虚假值？

Question

I want to check a bunch of variables for falsy values.

Instead of writing a very long if statement, eg:

if (!userData.email || !userData.lastName || ! userData.firstName etc...

I wanted to put these values in an array and simply check the array, eg:

      var detailsConditionsArr = [
        userData.firstName,
        userData.lastName,
        userData.email,
        userData.phone,
        userData.address,
        userData.mailAddress,
      ]

      if (detailsConditionsArr.indexOf(false) === 1) {
        console.log("Found a falsy");
      }

But the above doesn't work (if statement never fires).

The values could be false , null or '' .

Is there a way to check these from the array?

Answer 1

Ideal use case for Array#some

Check for falsy value in the iteration, if the test succeeds, true will be returned.

 var A = ["Name", ""]; var B = ["Name", "30"]; var C = ["Name", "30", null]; if (A.some(el => !el)) { console.log("Found a falsy in A"); } if (B.some(el => !el)) { console.log("Found a falsy in B"); } if (C.some(el => !el)) { console.log("Found a falsy in C"); }

Answer 2

You can use the key names you want to check as an array, then do the check like this:

 const userData = { email: '', lastName: '', firstName: '' }; const hasFalsy = ['email', 'lastName', 'firstName'].some(k => !Boolean(userData[k])); if (hasFalsy) { console.log('found a falsy'); }

Answer 3

You can use reduce to return a single value from the array like so:

var detailsConditionsArr = [
    userData.firstName,
    userData.lastName,
    userData.email,
    userData.phone,
    userData.address,
    userData.mailAddress,
  ]

if (detailsConditionsArr.reduce((carry, el)=> el ? carry : true, false)) {
  console.log("Found a falsy");
}

Answer 4

You can use some method.

 var detailsConditionsArr = [ "test", 12, false, "s", "sd", "test", ] if (detailsConditionsArr.some(x => !x)) { console.log("Found a falsy"); } // or //if (detailsConditionsArr.some(x => !Boolean(x))) { // console.log("Found a falsy"); //}

Answer 5

You can loop the list of properties and then check if any is falsy :

 const userData = { firstName : 'John', lastName : 'Doe', email : null, phone : 42, address : 'Hello', mailAddress : 'world' }; function HasObjectAnyFalsyValues(obj) { for (let prop in obj) { if (Object.prototype.hasOwnProperty.call(obj, prop) && !obj[prop]) { // <-- check for falsy return true; } } return false; } console.log('The object has ' + (!HasObjectAnyFalsyValues(userData) ? 'no ' : '') + 'falsy values');

This will check all properties . If you want to list specific properties instead, use one of the other answers posted

Answer 6

Using some is a clean way for doing this job.

The Array.prototype.some() method tests whether at least one element in the array passes the test implemented by the provided function (in your case, falsy value).

 const userData = {}; userData.firstName = "dd"; userData.lastName = false; userData.email = 0; userData.phone = 123; userData.address = "aad"; userData.mailAddress = "dff"; const detailsConditionsArr = [ userData.firstName, userData.lastName, userData.email, userData.phone, userData.address, userData.mailAddress, ] const detailsConditionsArr2 = [true, 1, "fff"]; const doesHaveFalsy = obj => obj.some(x => !x); if (doesHaveFalsy(detailsConditionsArr)) { console.log("detailsConditionsArr Found a falsy"); } if (doesHaveFalsy(detailsConditionsArr2)) { console.log("detailsConditionsArr2 Found a falsy"); }

More about some - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some