This is the tenth day of my participation in the August Text Challenge.More challenges in August

If statement

The if statement is used to perform conditional judgments.

    let a = 1;
    let b = 2;
    if(a > b){
        console.log("A is smaller than B");
    }
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The do while statement

Do while statements do and then judge, meaning that the statement inside the loop is executed at least once

    let x = "";
    let i = 0;
    do { 
    x = x +"The number is " + i + "\n"
    i++; 
    } while (i<5);
    console.log(x)
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For statement

The for loop can be nested, such as the classic output 9 by 9 times table

    let result = "";
    for(let i = 1; i <10; i++){for(j = 1; j <= i; j++){ result +=` ${j} * ${i} = ${i*j} `
        }
        result +="\n"
    }
    console.log(result)
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The for in statement

The for in statement can be used to iterate over all array elements in an array or over all attributes of an object.

   let txt = "";
    var content = { name: "juejin".time: 2021.huodong: "August Essay Contest" };
    var x;
    for (x in content) {
        txt += content[x] + "";
    }
    console.log(txt);
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The for of statements

The essential difference with for-in is that for-of iterates over the value of an array or object.

    let arr = [2021.'juejin'."August".'Essay Call'.'the first'.10."Article"];
    for (let i of arr) {
        console.log(i);
    }
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Switch beyond constant-like statement

Used to select one of several code blocks, similar to if, which jumps out of the switch code block if JavaScript encounters the break keyword. This stops the execution of more code in the block as well as case testing. If a match is found and the task is completed, execution is broken randomly. No more testing required. Break saves a lot of execution time because it “ignores” the execution of other code in the Switch block. You don’t have to break the last case in the switch block. This is where the code block ends naturally.

    let num = 10;
    switch (true) {
	case num < 0:
		console.log("Less than 0.");
		break;
	case num >= 0 && num <= 10:
		console.log("Between 0 and 10.");
		break;
	case num > 10 && num <= 20:
		console.log("Between 10 and 20.");
		break;
	default:
		console.log("More than 20.");
}
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With statement

The purpose of the with statement is to set the code scope to a specific object. Use it sparingly; otherwise, performance will be affected.

    var sMessage = "hello";
    with(sMessage) {
      alert(toUpperCase());	
    }
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In this case, the with statement is used for strings, so when the toUpperCase() method is called, the interpreter checks whether it is a local function. If not, it checks the pseudo object sMessage to see if it is a method of that object. Alert then prints “HELLO” because the interpreter found the toUpperCase() method for the string “HELLO”.