javascript配列コピー

44969 ワード
javascript
javascript配列コピー
  • ケース1(aとbはともに配列):
    // var  
var a = [1, 1, 1];
var b = [...a];

console.log(b);		// `b`: [1, 1, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a === b);	// false

b[1] = 0;
console.log(b);		// `b`: [1, 0, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a === b);	// false


// let  
let a = [1, 1, 1];
let b = [...a];

console.log(b);		// `b`: [1, 1, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a === b);	// false

b[1] = 0;
console.log(b);		// `b`: [1, 0, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a === b);	// false


// const  
const a = [1, 1, 1];
const b = [...a];

console.log(b);		// `b`: [1, 1, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a === b);	// false

b[1] = 0;
console.log(b);		// `b`: [1, 0, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a === b);	// false
  • ケース2(aは対象、bは配列):
    // var  

// case1
var a = {
       
    state: [1, 1, 1]
}
// !!!    
var b = [...a.state];

console.log(b);		// `b`: [1, 1, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a.state === b);	// false

b[1] = 0;
console.log(b);		// `b`: [1, 0, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a.state === b);	// false

// case2
var a = {
       
    state: [1, 1, 1]
}
// !!!    
var {
       state: b} = a;

console.log(b);		// `b`: [1, 1, 1]
// !!!
console.log(a);		// !!!? `a`: [1, 0, 1]
console.log(a.state === b);	// true

b[1] = 0;
console.log(b);		// `b`: [1, 0, 1]
console.log(a);		// !!! `a`: [1, 0, 1]
console.log(a.state === b);	// true


// let   

// case1
let a = {
       
    state: [1, 1, 1]
}
let b = [...a.state];

console.log(b);		// `b`: [1, 1, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a.state === b);	// false

b[1] = 0;
console.log(b);		// `b`: [1, 0, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a.state === b);	// false

// case2
let a = {
       
    state: [1, 1, 1]
}
let {
       state: b} = a;

console.log(b);		// `b`: [1, 1, 1]
console.log(a);		// `a`: [1, 0, 1]
console.log(a.state === b);	// true

b[1] = 0;
console.log(b);		// `b`: [1, 0, 1]
console.log(a);		// `a`: [1, 0, 1]
console.log(a.state === b);	// true


// const  

// case1
const a = {
       
    state: [1, 1, 1]
}
const b = [...a.state];

console.log(b);		// `b`: [1, 1, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a.state === b);	// false

b[1] = 0;
console.log(b);		// `b`: [1, 0, 1]
console.log(a);		// `a`: [1, 1, 1]
console.log(a.state === b);	// false

// case2
const a = {
       
    state: [1, 1, 1]
}
const {
       state: b} = a;

console.log(b);		// `b`: [1, 1, 1]
console.log(a);		// !!!? `a`: [1, 0, 1]
console.log(a.state === b);	// true

b[1] = 0;
console.log(b);		// `b`: [1, 0, 1]
console.log(a);		// `a`: [1, 0, 1]
console.log(a.state === b);	// true
  • ケース3(aとbはともに対象):
    // var  

// case1
var a = {
       
    state: [1, 1, 1]
}

var b = {
       };
b.state = [...a.state];

console.log(b.state);		// `b.state`: [1, 1, 1]
console.log(a.state);		// `a.state`: [1, 1, 1]
console.log(a.state === b.state);	// false

b.state[1] = 0;
console.log(b.state);		// `b.state`: [1, 0, 1]
console.log(a.state);		// `a.state`: [1, 1, 1]
console.log(a.state === b.state);	// false

// case2
var a = {
       
    state: [1, 1, 1]
}

var b = {
       };
({
       state: b.state} = a);

console.log(b.state);	// `b.state`: [1, 1, 1]
//    a.state  [1, 1, 1]
console.log(a.state);	// `a.state`: [1, 1, 1]
console.log(a.state === b.state);	// true

b.state[1] = 0;
console.log(b.state);	// `b.state`: [1, 0, 1]
console.log(a.state);	// `a.state`: [1, 0, 1]
console.log(a.state === b.state);	// true


// let  

// case1
let a = {
       
    state: [1, 1, 1]
}

let b = {
       };
b.state = [...a.state];

console.log(b.state);		// `b.state`: [1, 1, 1]
console.log(a.state);		// `a.state`: [1, 1, 1]
console.log(a.state === b.state);	// false

b.state[1] = 0;
console.log(b.state);		// `b.state`: [1, 0, 1]
console.log(a.state);		// `a.state`: [1, 1, 1]
console.log(a.state === b.state);	// false

// case2
let a = {
       
    state: [1, 1, 1]
}

let b = {
       };
({
       state: b.state} = a);

console.log(b.state);	// `b.state`: [1, 1, 1]
console.log(a.state);	// `a.state`: [1, 1, 1]
console.log(a.state === b.state);	// true

b.state[1] = 0;
console.log(b.state);	// `b.state`: [1, 0, 1]
console.log(a.state);	// `a.state`: [1, 0, 1]
console.log(a.state === b.state);	// true


// const  

// case1
const a = {
       
    state: [1, 1, 1]
}

const b = {
       };
b.state = [...a.state];

console.log(b.state);		// `b.state`: [1, 1, 1]
console.log(a.state);		// `a.state`: [1, 1, 1]
console.log(a.state === b.state);	// false

b.state[1] = 0;
console.log(b.state);		// `b.state`: [1, 0, 1]
console.log(a.state);		// `a.state`: [1, 1, 1]
console.log(a.state === b.state);	// false

// case2
const a = {
       
    state: [1, 1, 1]
}

const b = {
       };
({
       state: b.state} = a);

console.log(b.state);	// `b.state`: [1, 1, 1]
console.log(a.state);	// `a.state`: [1, 1, 1]
console.log(a.state === b.state);	// true

b.state[1] = 0;
console.log(b.state);	// `b.state`: [1, 0, 1]
console.log(a.state);	// `a.state`: [1, 0, 1]
console.log(a.state === b.state);	// true
    • javascriptは、1つの配列の重複要素と個数を取得します.