How to efficiently evaluate multiple conditions in an IF statement and check for emptiness using JavaScript

Question

How to efficiently evaluate multiple conditions in an IF statement and check for emptiness using JavaScript

I need help with formulating an if statement to check whether a certain condition matches one of those strings and is empty. I am having trouble wording it properly and finding the right syntax for it. This might seem basic, but I can't figure out how to search for it on google. Thank you in advance!

if(condition1 == "string" || condition2 == "string" && is empty){
    do this
}

javascript

Answer 1

Answer №1

Edit: Revised based on the jsFiddle you provided

// Accessing nested objects
var colField = evt.cell.field; // Obtaining column names from the grid in dojo
var mystring = item[colField] || ""; // Retrieving item based on colField property
var fields = ["Owner", "Home", "Realtor", "Broker"]; // Array of fields to compare against colField

// Checking if Owner, Home, Realtor, or Broker columns are empty in the object
if(fields.indexOf(colField) !== -1 && mystring === "") {

}

Updated jsFiddle: http://jsfiddle.net/3AXN7/4/

Since you have multiple columns to check, it's better to store all the column names in an array and then verify if colField exists in the array instead of using multiple conditions in the if statement.

The issue with this approach is that indexOf is not compatible with IE6-8. To ensure cross-browser compatibility, you can include a polyfill for indexOf function like this:

if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function (searchElement /*, fromIndex */) {
    "use strict";

    if (this === void 0 || this === null)
      throw new TypeError();

    var t = Object(this);
    var len = t.length >>> 0;
    if (len === 0)
      return -1;

    var n = 0;
    if (arguments.length > 0) {
      n = Number(arguments[1]);
      if (n !== n)
        n = 0;
      else if (n !== 0 && n !== (1 / 0) && n !== -(1 / 0))
        n = (n > 0 || -1) * Math.floor(Math.abs(n));
    }

    if (n >= len)
      return -1;

    var k = n >= 0
          ? n
          : Math.max(len - Math.abs(n), 0);

    for (; k < len; k++) {
      if (k in t && t[k] === searchElement)
        return k;
    }

    return -1;
  };
}

Answer 2

Edit: Revised based on the jsFiddle you provided

// Accessing nested objects
var colField = evt.cell.field; // Obtaining column names from the grid in dojo
var mystring = item[colField] || ""; // Retrieving item based on colField property
var fields = ["Owner", "Home", "Realtor", "Broker"]; // Array of fields to compare against colField

// Checking if Owner, Home, Realtor, or Broker columns are empty in the object
if(fields.indexOf(colField) !== -1 && mystring === "") {

}

Updated jsFiddle: http://jsfiddle.net/3AXN7/4/

Since you have multiple columns to check, it's better to store all the column names in an array and then verify if colField exists in the array instead of using multiple conditions in the if statement.

The issue with this approach is that indexOf is not compatible with IE6-8. To ensure cross-browser compatibility, you can include a polyfill for indexOf function like this:

if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function (searchElement /*, fromIndex */) {
    "use strict";

    if (this === void 0 || this === null)
      throw new TypeError();

    var t = Object(this);
    var len = t.length >>> 0;
    if (len === 0)
      return -1;

    var n = 0;
    if (arguments.length > 0) {
      n = Number(arguments[1]);
      if (n !== n)
        n = 0;
      else if (n !== 0 && n !== (1 / 0) && n !== -(1 / 0))
        n = (n > 0 || -1) * Math.floor(Math.abs(n));
    }

    if (n >= len)
      return -1;

    var k = n >= 0
          ? n
          : Math.max(len - Math.abs(n), 0);

    for (; k < len; k++) {
      if (k in t && t[k] === searchElement)
        return k;
    }

    return -1;
  };
}

Answer 3

Answer №2

if ((typeof condition1 === 'string' && condition1.length === 0) || (typeof condition2 === 'string' && condition2.length === 0))

Let's break this down further. The first part,

(typeof condition1 === 'string' && condition1.length === 0)

, simply verifies that the variable is a string and has a length of 0. If this condition is false, it then checks if condition2 is a string with a length of 0. If either one of these conditions is true, the if statement will evaluate to true.

Answer 4

if ((typeof condition1 === 'string' && condition1.length === 0) || (typeof condition2 === 'string' && condition2.length === 0))

Let's break this down further. The first part,

(typeof condition1 === 'string' && condition1.length === 0)

, simply verifies that the variable is a string and has a length of 0. If this condition is false, it then checks if condition2 is a string with a length of 0. If either one of these conditions is true, the if statement will evaluate to true.

How to efficiently evaluate multiple conditions in an IF statement and check for emptiness using JavaScript

Answer №1

Answer №2

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