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Slice() and slice() methods of arrays in JS

2022-06-25 12:38:00 【Fall in love with*】

slice() You can extract a specified element from an array , Specify how the element is indexed
             This method does not change its own array , Instead, the extracted elements are encapsulated into a new array and returned
             It should be noted that ：
             Intercept the starting index , Include start index
             Intercepted index , Does not include end index
             arr.slice(3,5) The inclusion index is 3 Value But does not contain an index of 5 Value
             
             arr.slice(a,b) The second parameter can be omitted , All elements from the beginning of the index will be intercepted
             
           Note that an index can assign a value to Arrays can be -1 Start From back to front -1 The last one -2 second to last

 splice() Delete the element and add a new element to the array
             Use splice() Will affect the original array , And return the deleted element as the return value
             It should be noted that ：
            splice(a,b,c) a Is the index of the start position b Is the number of deletions c And later you can add any element

            splice() Method can not only delete elements You can also add new elements based on the deleted elements 

<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script type="text/javascript">
		
			/* 
			 slice() You can extract a specified element from an array , Specify how the element is indexed 
			  This method does not change its own array , Instead, the extracted elements are encapsulated into a new array and returned 
			  It should be noted that ：
			  Intercept the starting index , Include start index 
			  Intercepted index , Does not include end index 
			 arr.slice(3,5) The inclusion index is 3 Value   But does not contain an index of 5 Value 
			 
			 arr.slice(a,b) The second parameter can be omitted , All elements from the beginning of the index will be intercepted 
			 
			  Note that an index can assign a value to   Arrays can be -1 Start   From back to front  -1 The last one  -2 second to last 
			 */
			var arr = [90,23,98,56,53,23,12,6];
			var result = arr.slice(3,7);
			console.log(result);
			// Will be output {"0":56,"1":53,"2":23,"3":12,"length":4}
			var result1 = arr.slice(2);
			console.log(result1);
			// Will be output {"0":98,"1":56,"2":53,"3":23,"4":12,"5":6,"length":6}
			var result2 = arr.slice(1,-3);
			console.log(result2);	
			// Will be output {"0":23,"1":98,"2":56,"3":53,"length":4}
			
			/* 
			 splice() Delete the element and add a new element to the array 
			 Use splice() Will affect the original array , And return the deleted element as the return value 
			 It should be noted that ：
			splice(a,b,c) a Is the index of the start position  b Is the number of deletions  c And later you can add any element 
			 */			
			arr.splice(0,2);
			console.log(arr);
			// Will be output {"0":53,"1":23,"2":12,"3":6,"length":4}
			var result3 = arr.splice(0,2);
			console.log(result3);
			// Will be output  {"0":98,"1":56,"length":2}
			// Will be output 
			//splice() Method can not only delete elements   You can also add new elements based on the deleted elements 
			
			
			arr.splice(0,3,"100");
			console.log(arr);
			 // Will be output {"0":"100","1":56,"2":53,"3":23,"4":12,"5":6,"length":6}
		</script>
	</head>
	<body>
	</body>
</html>

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