some循环

const arr = [1,2,3,4,5]
arr.some((item,index)=>{
    console.log('打印的次数')
    if(item === '3'){
    consolo.log(index)
    // 再找到对应的项之后，可以通过return true 固定语法，来终止some循环
    return true
    }
})

every判断

        const arr=[
            {id:1,name:'watermelon',state:true},
            {id:2,name:'liulian',state:true},
            {id:3,name:'caomei',state:true},
        ]

        // 需求判断
        const result = arr.every(item=>item.state)
        console.log(result);

reduce方法

        const arr=[
            {id:1,name:'watermelon',state:true,price: 10 , count: 1},
            {id:2,name:'liulian',state:false,price: 80,count: 2},
            {id:3,name:'caomei',state:true,price: 20,count: 3},
        ]

        // 需求: 把购物车数组中，已勾选的水果，总价累加起来
        let amt = 0
        arr.filter(item=>item.state).forEach(item =>{
            amt += item.price * item.count
        })
        console.log(amt);

        // arr.filter(item=>itemstate).reduce((累加的结果,当前循环项)=>{},初始值)
        const result = arr.filter(item=>item.state).reduce((amd,item)=>{
           return amd += item.price*item.count
        },0)
        console.log(result);