常用的循环遍历
forEach()
遍历数组
arr.forEach((el,ix) => {})
map()
遍历并返回处理后的数组
arr.map((el,ix) => {})
for of
for(let item of res){
console.log(item);
}
filter() || findIndex
返回符合条件所有元素的数组
arr.filter((el,ix) => {})
some() || every()
检测数组元素中是否有元素符合指定条件,返回逻辑值
- every:一假即假
- some:一真即真
const hasOneOf = (targetarr, arr) => {
return targetarr.some(_ => arr.indexOf(_) > -1)
};
reduce || reduceRight()
函数作为累加器-从左到右
var result = [
{subject: 'math',score: 88},
{subject: 'chinese',score: 95},
{subject: 'english',score: 80}
];
result.reduce(function(res, cus){
res[cus.subject] = cus.score;
return res;
},{});
var arrString = 'abcdaabc';
arrString.split('').reduce(function(res, cur) {
res[cur] ? res[cur] ++ : res[cur] = 1
return res;
}, {})