js之遍历数组的一些方法
程序开发
2023-09-13 15:12:38
有几种方法可以遍历数组，下面将逐个罗列！
while循环
let index = 0;
const array = [1, 2, 3, 4, 5];while (index < array.length) {console.log(array[index]);index++;
}
for循环
const array = [1,2,3,4,5];
for(let index=0;index
forEach
const array=[1,2,3,4,5];
array.forEach(function(current_value,index,array){console.log(`At index ${index} in array ${array} the value is ${current_value}`)
})
map
最后一个构造很有用，但是不会返回新数组，这对于你的特定情况可能是不希望的。map通过对每个元素应用一个函数然后返回新数组来解决此问题。const array = [1,2,3,4,5];
const square = x =>Math.pow(x,2);
const squares = array.map(square);
console.log(`${array}`);
console.log(`${squares}`)
reduce
reduce()方法对累加器和数组中的每个元素(从左到右)应用一个函数，以将其减小为单个值const array = [1,2,3,4,5];
const sum = (x,y) => x + y;const array_sum = array.reduce(sum,0);
console.log(`the sum of arrray:${array} is ${array_sum}`);
filter
根据布尔函数过滤筛选数组中的元素const array = [1,2,3,4,5];
const even = x => x%2 === 0;
const even_array = array.filter(even);
console.log(`even numbers in array ${array} : ${even_array}`);
every
得到了一个数组，想测试每个元素是否满足给定条件const array = [1,2,3,4,5,8];
const under_six = x => x<6;
if(array.every(under_six)){console.log(`every elemnet in the array is less than 6`);
}
else{console.log(`at least one element in the array was bigger than 6`);
}
some
测试是否至少有一个元素与布尔函数匹配const array = [2,4,5,6,8];
const over_five = x => x>5;if(array.some(over_five)){console.log(`at least one element bigger than 5 was found`);
}
else{console.log(`no element bigger than 5 was found`);
}
到此就结束啦，如果还有其他的欢迎补充！
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