[英]Uint8Array(8) stringification
由于IEEE 754,我无法从后端将无符号的64位整数获取到ArrayBuffer中,因此无法将此序列保持为Number。 有什么办法可以“串化”这个庞大的数字吗?
简而言之:
var buffer = new ArrayBuffer(8);
var raw = new Uint8Array(buffer);
raw[0] = 255;
raw[1] = 255;
raw[2] = 255;
raw[3] = 255;
raw[4] = 255;
raw[5] = 255;
raw[6] = 255;
raw[7] = 255;
var view = new DataView(buffer);
var result = view.getUint64(0); /// :-(
先感谢您。
是的,您可以对Int64进行字符串化处理,但是没有“内置”方法可以执行此操作,因为就像您所说的那样,JavaScript数字是双精度浮点数。
// ...
function readInt64(view){
var small = view.getUint32(0).toString(16); // present as base 16 string
var large = view.getUint32(1).toString(16);
// in a power-of-2 base it's just a string concat to add them
var bigNumber = large + small;
return h2d(bigNumber);
}
这里的答案来自h2d。
function h2d(s) { // https://stackoverflow.com/a/12533838/1348195 function add(x, y) { var c = 0, r = []; var x = x.split('').map(Number); var y = y.split('').map(Number); while(x.length || y.length) { var s = (x.pop() || 0) + (y.pop() || 0) + c; r.unshift(s < 10 ? s : s - 10); c = s < 10 ? 0 : 1; } if(c) r.unshift(c); return r.join(''); } var dec = '0'; s.split('').forEach(function(chr) { var n = parseInt(chr, 16); for(var t = 8; t; t >>= 1) { dec = add(dec, dec); if(n & t) dec = add(dec, '1'); } }); return dec; } function readInt64(view, i){ var small = view.getUint32(0 + 2 * i).toString(16); // present as base 16 string var large = view.getUint32(1 + 2 * i).toString(16); // in a power-of-2 base it's just a string concat to add them var bigNumber = large + small; return h2d(bigNumber); } var buffer = new ArrayBuffer(8); var raw = new Uint8Array(buffer); raw[0] = 255; raw[1] = 255; raw[2] = 255; raw[3] = 255; raw[4] = 255; raw[5] = 255; raw[6] = 255; raw[7] = 255; var view = new DataView(buffer); var result = readInt64(view, 0); document.body.innerHTML = result;
下面的DataView.getUint64()
实现将为您提供一个数值精度DataView.getUint64()
的数字:
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