JavaScript - 数组的迭代方法

数组的迭代方法：forEach() map() filter() some() every() reduce() find() findIndex()

    let arr = [
        {
            name: "Att1",
            age: 20
        },
        {
            name: "Att2",
            age: 30
        },
        {
            name: "Att3",
            age: 40
        },
    ]
    
    //遍历数组
    arr.forEach(item => item.gender = '男')
    
    //返回符合条件的新数组
    console.log(arr.map(item => '姓名：' + item.name));
    console.log(arr.map(item => item.age));
    
    //过滤 把符合条件的元素放到新数组中返回
    console.log(arr.filter(item => item.age >= 30));
    
    //是否存在 一真即真 返回Boolean值
    console.log(arr.some(item => item.age === 20));
    
    //是否全部都是 一假即假 返回Boolean值
    console.log(arr.every(item => item.gender === '男'));
    
    //统计 求值加和
    console.log(arr.reduce((total, current) => total + current.age, 0));
    
    //返回符合条件的第一个数组
    console.log(arr.find(item => item.name === "Att2"));

    //返回第一个元素的索引值
    console.log(arr.findIndex(item => item.name === "Att2"));