Similar Question:
Javascript - Checking for value in array
Can you spot the issue here?
var zipCodes =(['90001','90002','90003']);
Determine if a specific value is present in the array zipCodes
if('90001' in zipCodes) {
alert('True');
};
Similar Question:
Javascript - Checking for value in array
Can you spot the issue here?
var zipCodes =(['90001','90002','90003']);
Determine if a specific value is present in the array zipCodes
if('90001' in zipCodes) {
alert('True');
};
When using the in operator, it examines property names rather than values.
Since it's dealing with an Array, the property names will correspond to the indices of the Array.
In a modern environment, you have the option to utilize Array.prototype.indexOf().
if(zipCodes.indexOf('90001') > -1) {
If your target includes environments lacking support for .indexOf(), you can incorporate the MDN fix.
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) // shortcut for verifying if it's NaN
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;
};
}
To determine if a specific value is present in an array, you can utilize the indexOf method to search for the position of the item within the array. If the item is not found in the array, a -1 will be returned:
let zipCodes =(['90001','90002','90003']);
zipCodes.indexOf('90001') // 0
zipCodes.indexOf('90002') // 1
zipCodes.indexOf('90003') // 2
zipCodes.indexOf('90004') // -1
if(zipCodes.indexOf('90001') != -1) {
alert('True');
};
For more information, visit
Consider using an object instead of an array for better efficiency. If all you need is to perform a lookup, objects are a more suitable choice.
var zipCodes = {"90001": true, "90002": true, "90003": true};
if ('90001' in zipCodes) {
alert('True');
}
Check out this jsfiddle link to see it in action: http://jsfiddle.net/jfriend00/ZNGTq/
If you're looking for a solution, consider implementing code similar to the following:
var zipCodes =(['90001','90002','90003']);
if (zipCodes.has('90001')) {
....
}
Array.prototype.has=function(v){
for (i=0;i<this.length;i++){
if (this[i]==v) return i;
}
return false;
}
For more detailed information, refer to this resource:
....
When using the in operator, it is important to understand that it checks for a specific property within an object. If you are looking to convert this functionality for use with arrays, check out this informative article on how to test for a value within a JavaScript array: Testing Value in JavaScript Array
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