一、关于取值
const obj = {
a:1,
b:2,
c:3,
d:4,
e:5,
}
const a = obj.a;
const b = obj.b;
const c = obj.c;
const d = obj.d;
const e = obj.e;
const f = obj.a + obj.d;
const g = obj.c + obj.e;
es6
const {
a,b,c,d,e} = obj;
const f = a + d;
const g = c+e;
//如果后端返回的数据不是你想要的字段
const {
a:a1} = obj;
console.log(a);//1
//ES6的解构赋值虽然好用。但是要注意解构的对象不能为undefined、null。否则会报错，故要给被解构的对象一个默认值。
const {
a,b,c,d,e} = obj || {
};
二数据合并
const a = [1,2,3];
const b = [1,5,6];
const c = a.concat(b);//[1,2,3,1,5,6]
const obj1 = {
a:1,
}
const obj2 = {
b:1,
}
const obj = Object.assign({
}, obj1, obj2);//{a:1,b:1}
es6
const a = [1,2,3];
const b = [1,5,6];
const c = [...new Set([...a,...b])];//[1,2,3,5,6]
const obj1 = {
a:1,
}
const obj2 = {
b:1,
}
const obj = {
...obj1,...obj2};//{a:1,b:1}
三、关于拼接字符串
const name = '小明';
const score = 59;
let result = '';
if(score > 60){
result = `${
name}的考试成绩及格`;
}else{
result = `${
name}的考试成绩不及格`;
}
es6
const name = '小明';
const score = 59;
//在${}中可以放入任意的JavaScript表达式，可以进行运算，以及引用对象属性。
const result = `${
name}${
score > 60?'的考试成绩及格':'的考试成绩不及格'}`;
四、关于if中判断条件的吐槽
if(
type == 1 ||
type == 2 ||
type == 3 ||
type == 4 ||
){
//...
}
es6
const condition = [1,2,3,4];
if( condition.includes(type) ){
//...
}
五、关于列表搜索
const a = [1,2,3,4,5];
const result = a.filter(
item =>{
return item === 3
}
)
es6
//find方法中找到符合条件的项，就不会继续遍历数组。
const a = [1,2,3,4,5];
const result = a.find(
item =>{
return item === 3
}
)
六、关于扁平化数组
const deps = {
'采购部':[1,2,3],
'人事部':[5,8,12],
'行政部':[5,14,79],
'运输部':[3,64,105],
}
let member = [];
for (let item in deps){
const value = deps[item];
if(Array.isArray(value)){
member = [...member,...value]
}
}
member = [...new Set(member)]
es6
const deps = {
'采购部':[1,2,3],
'人事部':[5,8,12],
'行政部':[5,14,79],
'运输部':[3,64,105],
}
let member = Object.values(deps).flat(Infinity);
七、关于获取对象属性值
const name = obj && obj.name;
es6
const name = obj?.name;
八、关于添加对象属性
let obj = {
};
let index = 1;
let key = `topic${
index}`;
obj[key] = '话题内容';
es6
let obj = {
};
let index = 1;
obj[`topic${
index}`] = '话题内容';
九、关于输入框非空的判断
if(value !== null && value !== undefined && value !== ''){
//...
}
es6
if((value??'') !== ''){
//...
}
十、关于异步函数
const fn1 = () =>{
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve(1);
}, 300);
});
}
const fn2 = () =>{
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve(2);
}, 600);
});
}
const fn = () =>{
fn1().then(res1 =>{
console.log(res1);// 1
fn2().then(res2 =>{
console.log(res2)
})
})
}
es6
const fn = async () =>{
const res1 = await fn1();
const res2 = await fn2();
console.log(res1);// 1
console.log(res2);// 2
}
const fn = () =>{
Promise.all([fn1(),fn2()]).then(res =>{
console.log(res);// [1,2]
})
}