记录些Es6的知识点

新增字符串函数

startsWith endsWith includes repeat

<script>
     const id = '342523199010113417';
     const fix = 'c';
     console.log(id.startsWith('34'));      ==> true  //从开头匹配
     console.log(id.startsWith('1990', 6)); ==> true   //从下标为6开始匹配
     console.log(id.endsWith('34',2));      ==> true   //倒序下标为2开始匹配
     console.log(id.includes('342523'));    ==> true   
     console.log(id.includes('342523',1));  ==> false  
     console.log(fix.repeat(5));            ==> ccccc   //重复
</script>

新增数组函数

find findIndex some every

<script>
        const array = [{
                'name': 'apples',
                'attr': 1
            },
            {
                'name': 'bananas',
                'attr': 2
            },
            {
                'name': 'cherries',
                'attr': 3
            }
        ];
        const result_1 = array.find(item => item.name === 'bananas');
        console.log(result_1);    ==> {name: "bananas", attr: 2}    //返回符合要求的对象
        const result_2 = array.findIndex(item => item.name === 'bananas');
        console.log(result_2);    ==> 1            //返回符合要求的下标
        const result_3 = array.some(item=>item.attr===2)
        console.log(result_3);    ==> true      //遍历对象，至少一个满足要求，返回布尔值
        const result_4 = array.every(item=>item.attr===2)
        console.log(result_4);    ==> false   //遍历对象，全部满足要求，返回布尔值
    </script>