javascript round to 2 decimal

inspiration that prompted me to create the popular data Interchange Format--json. JavaScript relies on global variables to connect, and all top-level variables of all compilation units are set up in a common namespace called global objects. This is a bad thing, because global variables are demons, and they are fundamental in JavaScript. javascript reserved wor

JavascripJavaScript is a programming language, and the browser has a JavaScript interpreter in it, so the browser can interpret and handle the code after it is written in the JavaScript language rules. First, how to write1. JavaScript code exists in form--方式一-->type="text/javascript"src="JS文件">/script>--方式二-->type="tex

chain to inherit the bridge parent class */subclass.prototype=new bridge (); subclass.prototype.constructor=subclass;/* the third step : Extended subclass Properties, referring to the parent class as a shared property of the subclass, called in the subclass of */SubClass.prototype.superClass=SuperClass.prototype; // here must be prototype, not the function itself *//Fourth step : to ensure the normal operation of the program mechanism, Make a little judgment */if (SuperClass.prototype.construc

/*Basic JavaScript Learning SummaryThis summary uses the DW to write, in order to debug conveniently, will affect the test part to write in the annotation form ****/All tests are shown with the alert () function1, if conditional sentence function funif () {var date = new Date ();//Get a new datevar time = date.gethours ();//Get the current hour from the dateif (Time Alert ("Good morning!" ");}else if (Time Alert ("Noon!");}else if (Time Alert ("The Af

differently depending on the position of the parentheses-this is because the semicolon insertion mechanism , when you choose to end a line of code without a semicolon, will fix it for you.This behavior can cause trouble, such as when you return an object literal, while the opening parenthesis is on the next line:You will be surprised if you want the function to return an object that contains the name attribute. Because of the implicit semicolon, the function returns undefined. The preceding cod

, this usage is not a good habit and is not recommended for everyone to use. Essentially, when you create an associative array, you create an array object's properties. In JavaScript, all variables are actually objects of some kind. For example, a Boolean value is an object of type Boolean. In the above example, you are actually adding the name, year, and living three properties to the lemon array. Ideally, you should not modify the properties of an a

have any connection.Because the capture is X's reference, so the above three functions see X is the same variable.This is important because the local variables in JavaScript are not all in the heap . At least GOOGLE V2 is not. But the x above line 3 must be "Born and live" in the heap , otherwise func1,get1, Get2 will work on the destroyed stack variable x , making the above program meaningless.In other words, the runtime cost of closures is to t

Many come to the cloud habitat community are to directly know how to use, here first directly give the common fault-tolerant code. The first: The cloud-dwelling community itself is using Copy Code code as follows: More reference to JavaScript fault-tolerant processing code (masking JS error) If a more detailed description can continue to look down. If the exception-handling code is well-designed, then the final presentation t

when convertingPaesrfloat() floating point numberParsefloat: Parses each character starting from the first string until it encounters an invalid floating-point number character. Note: In addition to the first decimal point,the second difference between parsefloat () and parseint () is that it will always ignore the leading 0. JavaScript Data TypesLearning Goals1. Mastering String2. Mastering the string tur

of 0 ~ 1;Math.max () \math.min ();MATH.AQRT () = calculates the square root;MATH.PSW (J, I); + = Calculates the i-th square of J;Math.floor (); = Math.floor (1.5) + 1;Math.ceil (); = Math.ceil (1.2) + 2;Math.Round (); = Math.Round (1.2) + 1; Math.Round (1.5) = 2;Math.sin () = Returns the sine of the specified number of degrees;Math.Cos () = Returns the cosine of the specified number of degrees;Math.atan2 (

can arbitrarily define a global variable anywhere. Small application seems very convenient, code into scale, after splitting the file, it is finished. Compiler regardless, we can tube.Two different ways:1. All written together, such as the top of the program, good management.2. Write a container of global variables and throw all the global variables in when you use them. Such benefits are also unified management for convenient retrieval.var variableb

Grammar:1. Case-sensitive!!2. Identifier: variable, function name, property name, parameter.1. The first character must be a letter, _, or $2. Other characters can be letters, _,, or numbers3. Notes:1. Single-line Comment://2. Multiline Comment:/* */4. Strict mode: Specify "Use strict" at the beginning of the function bodyfunction do () { "user strict"; fun

This program can be used to implement many common animation effects, including size conversion, location conversion, and fade-in and fade-out.Program Description: The principle of gradient effect is to use the timer to continuously set the value. If you want to slow down the effect, set a step (For details, refer to the JavaScript spring effect ).Here we only integrate the gradient properties (transparency, width, height, left, top) and use the same g

will return a value, and let the function end.function myFunction () { var x=5; return x;}The above function returns the value 5.Example:function MyFunction (b) { return A *b;} document.getElementById ("Demo"). innerhtml= MyFunction (4,3);The InnerHTML of the "demo" element will be: 12You can also use the return statement only if you want to exit the function. The return value is optional:function MyFunction (b) { if (a>b) { return; } x=a+B}If a is greater than B, t