How to output all elements of an array in JavaScript

Methods for JavaScript to output arrays: 1. Use "console.log(array name)" to output the array; 2. Use the for or for in statement to loop through the array; 3. Use forEach() to traverse the array and output the array. Elements; 4. Use map() to traverse the array and output the array elements.

The operating environment of this tutorial: Windows 7 system, JavaScript version 1.8.5, Dell G3 computer.

Method 1: Use console.log(array name) directly

var a = [5,10,20];
console.log(a);

Method 2: Use for/for in loop output array

var arr = [5,10,20];
for(var i=0;i<arr.length;i++){
console.log(arr[i]);
}

var arr = [5,10,20];
for(var key in arr){
console.log(arr[key]);
}

Method 3: forEach() traverses the array and loops the output array

var arr = [5,10,20];
function f(value) {
	console.log(value);
}
arr.forEach(f);

Method 4: map() method traverses the array and loops to output the array

var arr = [5,10,20];
function f(value) {
	return value;
}
var a=arr.map(f);
console.log(a);

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