typeof check: if (typeof str === "string") Checks if str is of type "string", which applies to string literals. It does not return "string" for new String() because new String() is an object. Fallback: return "another type"; Handles cases where str is neither a string literal ...
The variable is a String. But, one of the drawbacks of using typeof() is that when it is applied to the variable declared by the new String() constructor, then instead of returning a string, its return object as its data type. Hence, it does not recognize the strings created in this...
// Sample variablevarmyVar='Hello';// Test if variable is a stringif(typeofmyVar==='string'){alert('It is a string.');}else{alert('It is not a string.');} You can also define a custom function to check whether a variable is a string or not. ...
* @param {Object} value 元素值 */function isInArray(arr,value){ var index = $.inArray(value,arr); if(index >= 0){ return true; } return false; } 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 方法六、include()方法: arr.includes(searchElement)方法用来判断一个数组是否包含一个指定...
if(typeofmyVar==="string"){console.log("myVar is a string");}else{console.log("myVar is not a string");} Another way to check if a variable is a string is to use theinstanceofoperator, which returns true if an object is an instance of a particular constructor. For example, the ...
So just using theObject.keys, it does returntruewhen the object is empty ✅. But what happens when we create a new object instance using these other constructors. functionbadEmptyCheck(value){returnObject.keys(value).length===0;}badEmptyCheck(newString());// true 😱badEmptyCheck(newNum...
1. Use Object.keys Object.keys will return an array, which contains the property names of the object. If the length of the array is 0, then we know that the object is empty. function isEmpty(obj) { return **Object.keys(obj).length === 0**; } We can also check this using Objec...
判断时使用Object.prototype.toString.call( list )==='[object Array]'或者Object.prototype.toString.call( list )=='[object Array]',==或者===一样的效果。 测试3: 如果使用jquery,可以使用$.isArray(obj)的方法,如下: vara = ["A", "AA", "AAA"];if($.isArray(a)) { ...
4.Using string.match() method: To check if a string contains substring or not, use the Javascript match method. Javascript match method accepts a regular expression as a parameter and if the string contains the given substring it will return an object with details of index, substring,...
Step 1: We have to find out if the given string is a palindrome or not. So to do this task we will create a function called isPalindrome and in this function, we will pass a parameter of string as str. So for this str, we will check the palindrome condition. Step 2: After the...