大家好,又见面了,我是你们的朋友全栈君。
var arr = [1, 2, 3]
arr.forEach((value, index) => {
console.log('数组值:' + value);
console.log('数组索引:' + index);
})
var arr = [1, 2, 3]
var arr1 = arr.map((value, index) => {
return value * 2
})
console.log(arr1);
var arr = [1, 2, 3]
var arr2 = arr.filter((value, index) => {
return value > 1
})
console.log(arr2);
var arr = [1, 2, 3]
var flag = arr.every((value, index) => {
return value < 4
})
console.log(flag);
var arr = [1, 2, 3, 11]
var flag = arr.some((value, index) => {
return value > 10
})
console.log(flag);
var arr = [1, 2, 3, 11]
var flag = arr.includes(3, 0) //从0开始,找3
var flag1 = arr.includes(3, -1) //从-1 + arr.length 开始,找3
console.log(flag);
console.log(flag1);
var arr = [1, 2, 3]
var arr3 = arr.reduce((acc, cur) => {
console.log(acc + '--' + cur);
return acc + cur
})
console.log(arr3);
var arr4 = arr.reduce((acc, cur) => {
console.log(acc + '--' + cur);
return acc + cur
}, 4)
console.log(arr4);
var obj = {
id: 1,
pname: '小米',
price: 1999,
num: 2000
};
var arr = Object.keys(obj);
console.log(arr);
arr.forEach(function (value) {
console.log(value);
})
var obj = {
id: 1,
pname: '小米',
price: 1999
};
Object.defineProperty(obj, 'price', {
value: 1000,
//如果只为false不允许修改这个属性值,默认值也是false
writable: false,
// enumerable 如果值为false 则不允许遍历,默认的值是false
enumerable: false,
//configurable如果为false,则不允许删除这个属性,不允许在修改第三个参数里面的特性,默认false
configurable: false,
// get() {//当访问该属性时,会调用此函数。
// return value
// },
// set(newVal) {//当属性值被修改时,会调用此函数。
// value = newVal
// }
}) //--> obj.num = 1000
console.log(obj);
var obj = {
id: 1,
pname: '小米',
price: 1999,
num: 2000
};
var obj2 = {
id: 2,
pname: '华为',
price: 3999,
num: 2000
};
var newObj = Object.assign(obj, obj2);
console.log(newObj);
console.log(newObj === obj);
const person = {
isHuman: false,
printIntroduction: function () {
console.log(`My name is ${
this.name}. Am I human? ${
this.isHuman}`);
}
};
const me = Object.create(person);
console.log(me.__proto__ === person); //类似原型链
me.name = 'Matthew';
me.isHuman = true;
me.printIntroduction();
了解更多:MDN
发布者:全栈程序员栈长,转载请注明出处:https://javaforall.cn/140977.html原文链接:https://javaforall.cn