ES6使用 Array.includes 处理多重条件用法实例分析

// 条件语句
function test(fruit) {
 if (fruit == 'apple' || fruit == 'strawberry') {
 console.log('red');
 }
}

function test(fruit) {
 // 把条件提取到数组中
 const redFruits = ['apple', 'strawberry', 'cherry', 'cranberries'];
 if (redFruits.includes(fruit)) {
 console.log('red');
 }
}

var arr = ['a', 'b', 'c'];
arr.includes('c', 3);  //false
arr.includes('c', 100); // false

// 数组长度是3
// fromIndex 是 -100
// puted index 是 3 + (-100) = -97
 
var arr = ['a', 'b', 'c'];
arr.includes('a', -100); // true
arr.includes('b', -100); // true
arr.includes('c', -100); // true