clear | 易学教程

setTimeout — callback executed immediately? [duplicate]

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问题 This question already has answers here : Why is my function call that should be scheduled by setTimeout executed immediately? [duplicate] (3 answers) Closed 5 years ago . I want to let an element fade in, and stay on the page for 7 seconds before it fades out. And I can cancel it anytime. I defined the following functions. But when I called info_timeout.setup(ele, 'some msg here') , the ele just faded in and faded out immediately. Am I missing something? var info_timeout = { show_info:

Clear a selection in Firefox

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问题 I have this function function smth() { var container = null; var newContainer = null; if (window.getSelection) { // all browsers, except IE before version 9 alert("first if"); var selectionRange = window.getSelection(); if (selectionRange.rangeCount > 0) { var range = selectionRange.getRangeAt(0); container = range.commonAncestorContainer; newContainer = container; } } else { if (document.selection) { // Internet Explorer alert("second if"); var textRange = document.selection.createRange();

CSS - make div's inherit a height

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问题 I'm trying to make a box with rounded corners where the height and width of the div depends on the content, so it's automatically adjust to it... You can see the example here: http://pastehtml.com/view/1duizyf.html The problem is that i can't get the "test_mid_left" (black background) and "test_mid_right" (turquoise background) to inherit the height from the "test_mid_center" (green background). I have tried height: 100% and auto, but none of thoose work. So how do I get them to inherit the

Why does 'overflow: auto' clear floats? And why are clear floats needed?

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My question arose when I created my (first ever!) two columns. I have a wrapper for my left and right columns, but the wrapper's height didn't expand to fit the left and right columns with each floated to its side respectively. I found a solution online where it adds the style (is this the right word?) 'overflow: auto' to the wrapper. After some research, I've found several articles that explain what the overflow does, including this stackoverflow answer: Why "overflow: hidden" clears a float? However, nothing in my research explains in a way I can understand why the wrapper's height doesn't

How can I clear the content of a file?

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问题 I need to clear the contents of a particular file every time the applications starts. How do I do it? 回答1: You can use the File.WriteAllText method. System.IO.File.WriteAllText(@"Path/foo.bar",string.Empty); 回答2: This is what I did to clear the contents of the file without creating a new file as I didn't want the file to display new time of creation even when the application just updated its contents. FileStream fileStream = File.Open(<path>, FileMode.Open); /* * Set the length of filestream

How to clear an ImageView in Android?

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I am reusing ImageView s for my displays, but at some point I don't have values to put it. So how to clear an ImageView in Android? I've tried: mPhotoView.invalidate(); mPhotoView.setImageBitmap(null); None of them have cleared the view, it still shows previous image. Mario Lenci I used to do it with the dennis.sheppard solution: viewToUse.setImageResource(0); it works but it is not documented so it isn't really clear if it effects something else in the view (you can check the ImageView code if you like, i didn't). I think the best solution is: viewToUse.setImageResource(android.R.color

clearRect function doesn't clear the canvas

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I'm using this script on the body onmousemove function: function lineDraw() { // Get the context and the canvas: var canvas = document.getElementById("myCanvas"); var context = canvas.getContext("2d"); // Clear the last canvas context.clearRect(0, 0, canvas.width, canvas.height); // Draw the line: context.moveTo(0, 0); context.lineTo(event.clientX, event.clientY); context.stroke(); } It's supposed to clear the canvas each time I move the mouse around, and draw a new line, but it isn't working properly. I'm trying to solve it without using jQuery, mouse listeners or similar. Here is a demo:

Fastest way to recreate the ArrayList in a for loop

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问题 In Java, using the following function for a huge matrix X to print its column-distinct elements: // create the list of distinct values List<Integer> values = new ArrayList<Integer>(); // X is n * m int[][] matrix for (int j = 0, x; j < m; j++) { values.clear(); for (int i = 0; i < n; i++) { x = X[i][j]; if (values.contains(x)) continue; System.out.println(x); values.add(x); } } First I iterate by columns (index j) and inside by rows (index i). This function will be called millions of times

用before 和after 清除浮动

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1 <html lang="en"> 2 3 <head> 4 <meta charset="UTF-8"> 5 <meta name="viewport" content="width=device-width, initial-scale=1.0"> 6 <meta http-equiv="X-UA-Compatible" content="ie=edge"> 7 <title>清除浮动</title> 8 <style> 9 /* 清楚浮动方法 10 (1) :额外标签法 11 (2) :父级添加overflow 属性 12 通过BFC 的方式,可以实现清楚浮动的效果 13 可以给父级添加:overflow 为hideden | auto |scroll 14 (3) :使用after 伪元素 15 (4) :使用before 和after 双伪元素 16 --->额外标签法 17 通过浮动元素末尾添加一个字的标签: 例如:<div style="clear:both"> </div> 18 19 */ 20 21 .box1 { 22 width: 400px; 23 background: green; 24 /* 触发BFC ,如果内容自动清楚会导致隐藏效果 */ 25 /* overflow: hidden; */ 26 } 27 /*.clearfix:after

how to clear the screen in python [duplicate]

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Possible Duplicates: clear terminal in python How to clear python interpreter console? I'm trying to write a program in Python but I don't know how to clear the screen. I use both Windows and Linux and I use commands to clear the screen in those, but I don't know how to do it in Python. How do I use Python to clear the screen? Senthil Kumaran If you mean the screen where you have that interpreter prompt >>> you can do CTRL + L on Bash shell can help. Windows does not have equivalent. You can do import os os.system('cls') # on windows or os.system('clear') # on linux / os x 来源： https:/